Rpm 340 Cyl heads on a 318 !

FWIW for the Chevy rod + pistons combo..... Here is one combination that might work with the 318 if you can bore to 4.00":

• Icon forged 4.00" pistons IC792 with CH=1.678", Flat top with 2 valve reliefs
• Then use a 6.300" long Chevy rod, with 2.100" rod bearing.
• Grind down the SBM crank to that bearing size, and offset the center +.0125" higher.
• Resulting piston to deck height would be +.045" (if I computed it right) and with a bit of block decking, you can adjust that for a .035' or .040" quench gap.
• If you wanted even more CR, the the IC793 forged piston has a dome that can be massaged down a bit for whatever you might like.