The headers, intake, carb, and ignition system will all fit on any LA small block and will increase the power of the 318.
But I understand that the 318 heads were the lower flowing, smaller port and valve heads.
There seems to be a better selection of aftermarket small block heads now than 20 years ago when I built my 360.
The 360 uses the iron J heads, but with 2.02"/1.60" stainless valves, hardened exhaust seats, and some porting, mostly in the bowl area for the larger valves.
The stock heads needed a bunch of work. The quench area was a different depth on each head (it has KB-232 quench dome pistons), so the heads needed to be milled different amounts and then the chamber cc's checked and equalized. Also had to machine the spring pockets and valve guides for dual springs and PC seals, and ream the oil feed bolt hole(s) for extra oil clearance because using head studs.
Today it would be easier to just get aluminum heads than to do all the modifications to the stock heads.