A forged 360 Mag piston that comes in around 8- 8.5:1?

I could do that but I actually want to spend some money on a nicely done 360 engine. At 56 with my kids grown and gone and now some disposable income I'd like to do what I've not been able to afford to do in the past, and I want to do it right. I'm not afraid to spend some $$. Plus the 318 mag currently in may Dakota has 235,000 miles on it. The core 360 Mag I obtained is out of my brothers Ram and has 300,000 miles on it! It still ran good but consumed oil. Got it for free.
I know you’re doing a mild build, but for not very much more money you could get a complete stroker rotating assembly from scat, balanced and ready to basically set bearing clearance, and drop in. Put your ported magnum heads on it for now and have plenty of room for improvement later if you choose. It’ll be a torque monster. The blower and heads become a big limitation at that point though. Down the rabbit hole we go.