My car was a slant 6 that I built to 360 specs for the PSMCDR race in Stanton MI. I bought a complete 360 duster drivetrain from a rusted out donor. Cam was junk so I replaced it with a correct replacement and had a heads rebuilt with original valves. No new bearings or rings. That motor went 14.50@95ish with 90 psi of compression. The next year I put a new short block together with $100 eBay pistons (H405cp),same uncut heads,same cam, no "tricks". This is its current form. The only thing it has that an original car doesn't is I bought the short(3ft?) TTi exhaust pipes(2.5) and had a muffler shop bend the rest. So it has 2.5 exhaust pipes(1/2 TTi,1/2 compression bent), dynomax mufflers with 2.25 compression bent tail pipes. I guess to answer your question I did build it for purestock but I'm not taking advantage of the rules. For example you are allowed to run 1.5 points of compression over the advertised ratio. The 74 360 was advertised at 8.4:1 so by the rules I could run 9.9 and still be legal. Right now I'm at 8.8:1 with uncut heads and block with .028 gasket.