I didn't think you could punch out a 396 that much. You would have to bore it out .156, I didn't think that gm designed the cylinder walls to be taken out that far.five7kid said:
For a 427 I've always heard to get a 454 block with a 396 crank, since the 454 already has the 4.250 bore.
I've yet to build one, so I could be comletely wrong here. :dontknow: