'68 318 to carbed Magnum 5.2: Check my checklist

I can't answer with any certainty of course since I'm not there, but I used some reasonable numbers to calculate the estimate.

Std bore x stroke
0.045x4.15" gasket
0.040 deck clearance
10cc dish
72cc chambers

That netted 8.5, so I think it [and I can't stress this enough] should be about that. Fortunately, you have a 360 not a 318...you have some displacement to make up for those big chambers.

As far as potential for ping, as long as you tune the fuel delivery and timing correctly, and don't lug it, I think you'll be fine. People built up engines similar to this one for literally decades without issues so as long as you're putting things together with due diligence and setting it up correctly, you'll be fine.

That dial indicator setup should work just fine. Also consider since most pumps are selling ethanol blends, they have a better resistance to detonation since alcohols don't ignite as quickly as petroleum based fuels...you just have to tune for it.