Some advice
A 360 engine will probably have Speed Pro Hypers because of the price, not entirely what the compression would be with mid 70's 360 heads.
Probably JUST south of 9:1. Why worry about that? That's the least of your worries as long as compression is above 8:1 and it will be.
Once again, we can thank the magazine and forum geniuses for telling everyone their engine will run like crap with anything under 9.5. Just ain't true.
That 265 DEH is very similar to a Thumpr grind, BUT it's smaller and ground on a 110 and not a 107. It will build cylinder pressure in a similar manner. Hell, you could even jump up to the 275 DEH for a tad more chop and not lose much bottom end, but not in a 318. I think the 275 DEH would be a little large there.
Go to the Comp site and actually LOOK at those cams. Short intake duration, long exhaust duration and ground on a moderately tight 110 LSA. That's goin in the Thumpr direction without losing a lot of bottom end torque.
Don't choose the DEH line. I don't care. But if you go another route, it should be a similar grind.
Compression on a street engine is really not important. As long as it is not under 8:1 and not over 9.5, you will make respectable power without detonation.
Cylinder pressure is what you are looking to maximize. With a 360 you'll have a good bit of cubes for a small block, so stop the panic about compression. Those Speed Pros are what the two eyebrow? If so, you're looking at compression at or a touch over 9:1. The 4 eyebrow a little lower. You'll have plenty of compression either way. Get your panties in a wad about something else.