I can tell it's a small block Chevy, and that's about it. Maybe a reverse rotation water pump? with a serpentine setup--not that that'd impact oil choice. PS, AC, can't tell if PB. Alloy heads. Headers. All of which means... no idea what oil.
I'd plan on changing often. I'm not following the whole zinc controversy, 'cuz I'll never own something for which it matters, but a carb setup to me says "change early and often". If you're not going to run below 60F or so, then what the heck, 15W40. Maybe run a 5W30 for a bit, as a flush, and take out for a drive, just to see what the oil pressure does, if it seems to drop when hot, then you'll know it needs something thicker.
Maybe pop the valve cover and see if it has roller rockers (might be a good time to check lash). Not sure, can you use a borescope to snake down and see what kind of lifers it has? I want to say rollers "always" have some sort of tie bar across them, something to give away their presence in a SBC, but I'm probably wrong.