I have a Gen3 and a Gen2ish. They have the same casting number on the heads, so I assume the heads are the same. Mine is different to most Gen2's though so I can vouch for all yellow plug 1G's.
I have just put the GEN3 manifolds/turbos/ecu etc on the gen 2 engine and it seems to make similar power to the gen3, so I guess the cam specs are similar. Although the GEN 3 did seem to make power earlier, but that could just be because the GEN2 is a tired old motor.
as far as the rest of the internals, I can definitly say that there are a couple of different cranks in them.