Advice on which heads to use. 360 , 302???

You definitely don't want to use 360 heads on your 90 318. You'll only have about 7-1/2 to 8 to 1 compression. Those are just single springs with a damper. Not the same as dual springs. They should work fine so that's some good news. I know what it's like surviving these days and having to save a buck. Not buying the heads should help. The carb adapters work ok but not the best. Better off either getting a ThermoQuad or different intake. I see LD4B's advertised every once in awhile for $100. That's a good intake. Why are you thinking about swapping back to the original cam? I know a roller is good but the stock cam isn't much for performance. Although you can have it reground.