Porting 302's

I ran some figures on the Stan Weiss compression ratio calculator for you based on stock 1978 318 figures. If your fortunate enough for your heads to clean up to 60cc chambers and you use the NOS head gaskets, then you will have a bump in compression from 7.8 to about 8.6:1. If you have them cut .030, you can get about 8.9:1. I have a friend who has a set cut .050 to a 55 cc chamber, but he discovered he had to correct the rocker geometry with a flat tappet hydraulic. That would give you close to 9.2:1. That motor is in my possession now, it gulped water going dashboard deep through a creek, but those heads got a new set of stem seals and swapped onto another 318 and are still going with another owner now. Another option I have came across lately is a Chrysler LA marine .018 stainless shim head gaskets of unknown origin (at a marine parts warehouse, I suspect they’re offshore). But I would have to use them first myself before telling someone else to risk them. They would give you right at 9:1, but I wouldn’t even think about running them without getting the decks cleaned up, too.