I was checking out a few crate engine sites and there are 632 merlin blocks. They have the 4.75 stroke already, but only a 4.6 bore.
So I do believe it is very possible.
I've heard of bigger motors than 632, so I bet it would just take destroking one of those.
This might be just the motor for my 70 chevelle. I can see it now, jet black paint job with black tinted windows, side pipes, and a 666 under the hood. :devil:
Todd