How would you rebuild this 318?

Are you happy with the power output now? If so, All I would do is put a crank kit in it. You don't bore one "just cause you want to", you bore it if it needs it. Does it smoke now? Use any oil now? Those compression numbers IMO are pretty good with a non stock cam. That tells me rings and valves are sealing good. If you pull the whole thing out and go to boring and buying pistons, new cam and such, you're almost justifying finding a 360. I hate bein "that guy" cause I never am, but honestly, how much more power do you think you'll get with just an over bore and maybe a cam change? You ain't addin 100 HP. You could with a 360. I'm just saying that because I don't know what your expectations are. If all you want is something to cruise around in and have fun with, just repair what you have.