I'm doing the same thing on an extremely low buck 318 DD. Have some std pistons/moly rings and some viper rods (.098" longer). I dont care what the bore taper/out of round/clearance is. Shooting for .035-.040" quench and will machine piston notches to reduce the static CR. I'll decarbon the pistons/pins and rods in carb cleaner then weigh em then deburr/polish/trim the new rods/pistons (they're heavier) until the new piston/pin/rings weigh the same as the old and slap em in w some new bearings. You can get a HF digital gram scale (on sale) for less than 10 bucks and it is (so far) as accurate as my high dollar one (might not stay accurate forever) EDIT adding 302 heads/1&5/8 headers. Keeping the eddy 1406/streetmaster. An over the fender overhaul to use these std pistons I have and the headers that are hanging from the rafters and... it never ends