Yes, it does not matter which territory the troops on the transport are invading. The amphibious assault is in the sea zone adjacent to a territory with an airbase, which is all that is required.
Marsh
I know an air base allows fighters scrambling to defend an adjacent SZ.
But can fighters also scramble to defend a land territory adjacent to an Air-Base (i.e. can Russian fighter and tact-bomber in Moscow (with an Air-base) scramble to defend Smolenks?
(from a purely logical point of view I don’t see why they couldn’t, but the manual seems to imply that fighters can only scramble on a sea-zone).
Scrambling is only allowed in sea zones.
Just to provide logical justification: air units can’t scramble to provide air cover for adjacent provinces because those provinces can have their own fighters and/or airbase. Sea zones cannot, and the purpose of air bases in many cases is to help nearby fleets.