Camshaft for blown 360

I would think negative anything piston volume would be too much. A negative piston volume ADDS TO the piston volume which TAKES AWAY from the over all chamber volume and ADDS compression. Sometimes people get that reversed.

That said, I would run something with a 112 or 114 lobe separation. Beyond that, I would choose an appropriate lift that matched the rest of the build. As in matches your rocker arms and whatever shafts you're running and whatever RPM range you plan to run in "mostly". If this is a street cruiser, "I" would choose something no more than .550 lift with .050" duration from 220-250 but ground on a 112 or 114 LSA.