First, see the following post for some idea of my background.
http://www.axisandallies.org/forums/index.php?topic=18023.15, see reply #19, I am the Timerover51 quoted.
Second, the tanks used by the Marines in the Solomons, both at Guadalcanal and the Central Solomons, were M2A4 and M3 and M3A1 Stuarts, not Sheridans. One of them is still sitting in a marsh in the middle of Arundel Island near New Georgia and is a minor tourist attraction for the islanders.
Third, see the following for the organization and equipment of the Japanese Special Naval Landing Force units. It is the Handbook on Japanese Military Forces, Oct. 1944.
They were quite similar to the Marine Defense Battalion units and were not intended for use as an amphibious assault unit. The amphibious unit that was supposed to attack Midway was the 28th Infantry Regiment of the Japanese Army’s 7th Infantry Division, detailed to the Japanese Navy for amphibious operations, commanded by Col. Ichiki. One battalion of this unit, under command of Col. Ichiki, was the unit that attacked the Marine perimeter at the Battle of the Tenaru River, and was wiped out.
For the analysis of damage to the Yamato and Musashi, see the following Report of the US Naval Technical Mission to Japan, which is also summarized in Bill Dulin and Bill Garzke’s book, Axis and Neutral Battleships of WW2.
http://www.fischer-tropsch.org/primary_documents/gvt_reports/USNAVY/USNTMJ Reports/USNTMJ-200H-0745-0786 Report S-06-2.pdf
The report is in PDF format and can be downloaded and printed out.
For additional source material on the Pacific War, I would suggest looking at the following online source as a start, as it has a lot of the US government publications online, including the official and semi-official histories. As a minimum, you need to look at the official US Army history, Cartwheel: The Reduction of Rabaul, the Marine official history, The Isolation of Rabaul, S.E. Morison’s books on Guadalcanal and Breaking the Bismarck Barrier, Paul Dull’s Battle History of the Imperial Japanese Navy, and the official Army and Marine Corps histories of Guadalcanal. Shots Fired in Anger by Lt. Col. John George, who fought on both Guadalcanal and with Merrill’s Marauders, is an excellent source of information on infantry fighting in jungle terrain.
With respect to battleships, the US designed the 2 ships of the North Carolina class and the 4 ships of the South Dakota class prior to beginning the Iowa-class ships. The Washington, the North Carolina, and the South Dakota all saw use in the Guadalcanal series of naval battles. The US had only one battleship with 12 inch guns active in WW2, and that was the Arkansas, all of the other ships carried 14 inch or 16 inch guns on the Maryland-class of 3 ships. The 12 inch guns on the Alaska-class large cruisers were far more powerful than the guns on the Arkansas, firing an 1140 pound AP projectile verses an 870 pound AP projectile.
The book, The Amphibians Came to Conquer, posted on the above site, has a lot of maps covering the area of Guadalcanal and the Central Solomons, which you might want to take a look at. The maps are all capable of being downloaded.
I have developed a 6-player expansion of the original edition of Pacific, that can be located under House Rules-Pacific at the main site page, and have been playtesting and refining them for several years.
Lastly, aside from improved aircraft, the two main technological advances that occurred during the Solomon Islands campaign were good quality microwave radar, allowing for night actions where the US gradually reached a position of superiority over the Japanese by mid to late 1943, and the proximity fuze in the spring of 1943, which boosted US anti-aircraft effectiveness by 50%, from a 33% shoot down rate to a 50% shoot down rate of attacking Japanese aircraft. The Betty loss rate was even worse.
As for scale, you are looking at regimental-size units at most, and could go to battalion-sized units at the cost of having a few more figures on the board. In the jungle present in the Solomon Islands group, and the Southwest Pacific area in general, naval gunfire and artillery were of limited effectiveness against well-dug in infantry units. The shelling of air bases by naval gunfire was good only for temporary neutralization, and then only with a lavish expenditure of ammunition, say 4500 rounds of US 6 inch naval High Capacity rounds, and then maybe only for 24 to 48 hours. Remember, even the October 14th bombardment of Henderson Field by the Japanese battleships Kongo and Haruna only knocked out Henderson Field for the morning, and by afternoon, Marine planes were attacking the Japanese transports. Where artillery was most effective was in defensive fire against an attack, where the enemy was exposed in the open, rather than dug in. Close air support doctrine had not been developed as yet, and in heavy jungle, was apt to be ineffective at best, and dangerous to one’s own forces at the worst.
I am still working on a set of replacement rules for the Guadalcanal game, and will be using a 12-sided die roll to account for the addition of the cruiser to the ship mix, as well as the PT boats. I would recommend a 12-sided die for use in any A&A game where you have cruisers as part of the ship mix, or mechanized infantry or tactical attack aircraft. If you allow for tactical attack aircraft, then drastically reduce the effectiveness of fighters against ground units. The fighters used during this period, up to late 1943, simply did not have enough of a bomb load to be effective against larger ships or dug-in infantry or infantry in the jungle. The P-40 did become far more effective later, following modifications that allowed in to carry up to three 500 pound bombs or rockets. The Wildcat and Zero never were effective fighter-bombers, and the early Corsairs were all used as fighters, not fighter-bombers.
Tactical attack aircraft should have a higher attack value against ships than for ground units, and adjustments to hitting should be made based on terrain. Dug-in infantry in jungle should only be able to be taken out by attacking infantry with artillery support, and flamethrowers would be a boost as well.