Bet you still didn't measure the bores, did you? If they aren't round and straight you're wasting the price of new pistons, and may cost you even more when it blows up.
Nice and big, like an 8 mile whore.
.303 piston clearance and .045 ring gap it's a wonder you had that much compression.
Never trust a previos owner much. Always verify it yourself. Receipts, eyeball, micrometer, calipers, compression gage, etc