Big Block Mopars are 4.840" bore spacing. That is why they are called big blocks. The small blocks are less.(can't remember the actual measurement). The reason one is a big block and the other is small is the comparison between them. A small block guy wants a 4" stroke crank and has over 400 CID. So what that just means he can now turn less RPM to pump the same air. You can do the same thing with your big block, in fact you can go 4.5" in stroke.

But, something to keep in mind the 99" Hemi is not a Big block Mopar. Why because it is not 4.840 bore spacing. It is 4.900" So Al you have a Extra Big Block. He He He.

Leon