Ok Assuming both motors have the same heads, cam, compression ratio, intake, carb ,ect. wich motor will make more power?

A 400 block .060 over with a 350 crank and bearing spacers wich is like 382 cubes.

OR

A 350 block .030 over with a 400 crank to make 383 cubes.

 

These combos are basically like the old 377 vs. 383 debate. The destroked 400 will make more high rpm HP, while the stroked 350 will make more low end torque. I'd say they are basically equal it just depends what rpm level you are wanting to make power at.

 

The 383 would be way better off on the street and the 382 would be a way better circle track or trans am engine.

 

The correct combo you didn't list: the 400 block with the 400 crank.