For 500 hp any block should be fine as long as it sonic tests fine, most are still fine at that level even without testing if you don't go crazy on bore size.

The strongest production 360 block out there is a magnum block. Unless you are bent on running LA heads, in that case you got to get oil to the shaft somehow, either add an oil line, PR oil them and hope for the best, find a machine shop that can drill the hole through the deck and hit the cam bearing hole, or use a 89-92 block so you can still use the roller cam at least. If a big bore is the primary concern and you want to run flat tappet (or pay for conversion) then a 70-71 block is supposed to have thick bores but 40+ years of neglect tends to rot the cylinders from the water jacket side of things so again you need to sonic test.

Long story short run a magnum block with magnum based heads so you get the strongest, least corroded, roller set up, EFI ready for the future (or now).