Let's say we live in a perfect world where money isn't an issue. (I wish)

What engine could I throw in, what parts would I need - besides tranny and axles obviously.
How much would it cost to transfer the engine to the rear end? There's too much space back there to go to waste.

I already know of a 3S-GTE engine swap so that's out of the question.

What's a good engine for rallying?