If you're compression is really at 8.9:1, its not that bad. Obviously a little more would be better, but with the pistons .060 in the hole that might be hard to do. What thickness head gasket is that with? Mopar is reproducing a .024-.028 compressed thickness gasket now, Mancini has them. Worth almost a half a point over a standard .039 gasket.
I think you're in the ballpark hp-wise. The biggest limitations of the 318's were a stock compression that was actually more like 8:1 or less, and anemic heads. The RHS heads flow VERY well, and a compression ratio at 9:1 (or even close) is still better than stock. You might be able to do a little better with tuning, but the cam is going to limit how much advantage you ultimately get out of the heads. Cams aren't that horribly expensive, if you've already bought the heads you might as well bite the bullet and get a decent cam to run with them.