Compression/octane

Long one here. 70 340, 10.5, purple .484, 232 at .050. Not started for 20 years, then had to pull a head for stripped out threads, Found top of #6 piston missing at top land, found the last right bank factory piston remaining in the us. Pulled other head, all good.
Last driven in 87, ex-wife, who knows? regular gas?
My question is; what octane? pump hi? mix in race gas? Actual probably 9.5 compression? How much does that cam bleed off? 110 c/l, installed straight up. (x heads, 2.02, un touched.
Thanks, guys. Don't know whether to pull it and put in a 360 low compression. Which I don't want to do. Laid off. Oh, 4.88 4 link and manual reverse, 3000 stall. Don't think a low comp will work.