Some 360 engine improvements

If it is truly a 1971 360 the compression is probably smack on top of 8.5:1. The 71 had more compression than any of the rest because the pistons used had a taller compression height than any other year. You can get 9.1 real easy by milling the heads about .030" and running thin head gaskets. The .025" ones are on Ebay.