360 Heads on my 318?
IMO, unless you're 318 has quite a few mods, the 750 is a bit much carb and is probably really hurting you on the low end.
The 360 heads are fine to use on a 318, but what you gain in flow will be offset by lower compression. A 318 with 360 heads can run VERY well if the heads are shaved appropriately.
My friend ran a set of unmilled 360 heads on his 318 and it killed the low end. Ironically, the police 318 engines used the intake and heads from the 360 starting in 1978.