My idea of "stock bottom end" is NOT replacing pistons, rods, etc. - taking a production short block and installing a cam, heads, intake, etc. Given that, the compression ratio of the stock pistons would be the limiting factor. IMO your best bet would be putting a mild (hydraulic roller) cam, ported/decked heads, headers, and a carb intake on a 360 Magnum short block.

OK, you also mention NOS - by the time you buy the kit you could have bought decent pistons, and not have to keep buying NOS refills.

Best bang for the buck? 360 Magnum longblock (preferred 100K or less), better cam and valvesprings, carb and intake, headers, and a 125 shot.