if you're open to a piston and/or piston & head swap, KB167 pistons set up at 0 deck and either closed chambered 302 or magnum heads would make a very nice combo. do a search for hotroddave40 built an engine like this with a stock 273 solid cam, and it had crazy torque and delivers upper 20's for highway mileage in his A body with a lockup 904 and 2.76 gears. he's ~10:1 with short cam timing but the excellent quench characteristics from the 0 deck flat top/closed chambered heads allows him to run 89 octane without pinging.