I do know that the stroke is different and would confuse the compression issues but the pistons are the same but i think the bore is slightly different
There is also the loom,individual coils,exhaust maybe,ECU etc etc etc......
Physically the blocks are the same so mechanically the block should fit
I think you may have to use the 3.8 head but maybe the cam cover from the 3.6 ?
So you can use the distributor
What's the use ? maybe PPHILPOT head is damaged and he can only get the 3.8?