[blykins]

"Hey Matt, You can start with a 351W bore it .030 over and then stroke it 4.5 inches and that will result in 427.5 cu. in. Hope this helps.

That's a little too much stroke for a small block...I don't even think they make a 4.5" crank for a small block. 4.5" stroke would be 459ci.....hehehe....wouldn't that be nice....

If you're starting with a .030" overbore, you want about a 4.180" stroke...there are probably some aftermarket crank grinds that stroke...or you can offset grind one.

If you're staring with a .040", you want a 4.160" stroke...

And if you have a .060" overbore, you want a 4.125" stroke. I was shooting for that with my engine, but I didn't want to have to offset grind a 400M crank or have one specially made, so I just went with a 4.100" stroke and got 425ci. Close enough.