I hear their combustion chambers are on the large side for a stock 318 though, so even though they wouldn't be as bad as 360LA heads, probably wouldn't be your best option without a lower end overhaul and zero deck or close.
This isn't true: The 62 cc chamber on the RHS heads is smaller than any stock 318/360 head. The 302 heads supposedly have 58cc chambers, but my (limited) experience has been that they are closer to 70cc on average. No 318 is going to make good compression without a lower end refresh or some serious milling, the pistons are too far down in the hole. I can't for the life of me understand why they ever thought they needed valve reliefs in 318 pistons. The lift on the stock cam is less than the pistons are down in the cylinder!
If you are up for tackling the Magnum swap an a new set of heads, I'd give the Iron Ram heads from Hughes a look. They have 58cc chambers. If I would have milled them to 54cc, and run the .028 skinny head gaskets, I could have gotten my stock 318 shortblock all the way up to 9.5:1, but I didn't have any valve reliefs.
