If we assume a average capture of WR with 6 infantry surviving there and Germany stacks Karelia this battle is 61% to capture Karelia for Russia with the 2 tank build, assumes 2 infantry move from Okrug to Archangel as well, pretty normal. https://aa1942calc.com/#/E0q7VObBHRhUzhT3InP0sA
Note that this battle is not really a option without the tank build. That would only be 18% to capture instead of 61%. So 2 tanks better right?
The average results of this battle will only leave 2 to 4 ground units in Karelia if it succeeds at all, a third of the time it won’t. And it’s easy for Germany to then take it back and wipe out the Russian tanks again which will basically leave Russia with its round 2 build to work with after this.
Meanwhile if Russia builds the artillery instead and does not attack Karelia but puts everything into defending WR, maybe a light trade of Belarus or Ukraine round 2 it will face more German tanks on this attack round 2 but it has enough numbers to hold if UK and/or US help defend WR sending fighters there.
https://aa1942calc.com/#/A5EJBsZsBIWRk6bEB9L3CQ
You can fool around with these numbers but I do think you have more options with the artillery build in the case of below average results of the round one attacks than with the tank build, but you also are giving up the option to attack Karelia before Germany can go.
So it’s really up to you. Do you want to trade aggressively with Germany? If so I think you need to be doing KGF. Or do you want to play more defensively with Russia? Which does give Allies more options I think.
