built up 318 oddly low MPG's? hp rating?

alright good to know, there are a few non-ethanol places around where I live and I have tried a full tank on it, I didn't really notice much at all when it came to power and since it was $.60 more a gallon I just went back to regular. My plan is tomorrow reset and tune mu carb, floats, mixture, idle settings, choke, the works. Then drive it a bit, maybe invest in an MSD box. other than that I can't do much. Sounds like decking the heads is too much work, im not going to pull the engine so it may come down to putting it on a lift, pulling the oil pan and putting in new pistons. any recommendations on which ones at this point? i figure some good KB 9:1 pistons, maybe 9.5:1 if you guys think the heads are lowering my standard compression gouge number so i will end up with 9:1.