Chiphead, there is something different about your '68 327.....it's a
medium journal engine. This means the rods and mains are larger than earlier 327's and 283's.
The 283 was a smaller bore, so you can't build a "true" 283. You could make it a 302, but why?
Just bore the block and get a 350 crankshaft, balancer and pistons. Main and rod sizes are the same and you get more
cubes out of the deal. It doesn't cost any more to build a 350 than any other small block Chevy.....
.
Use "open" chamber heads (#441 is a good one) to keep the compression ratio down, get a decent camshaft and you will have a good running SBC.
Good Luck, whatever you decide
