LA318 Edelbrock Magnum v RHS LAX Heads

In general you don't want to mill heads any more than you "need" to because it screws around with the rocker/pushrod geometry as well as the intake manifold mating surface. I learned that straight from my machinist who has 40+ years of experience. It can help give you a bit more (like 0.25 increase in comp. ratio) but for larger increases the proper way to do it is to get taller pistons. This is why I asked, what pistons do you have?? If they are stock or stock-replacement advertised at 8:1 comp then iron heads will be better.

As far as oiling goes, you can use Magnum heads on LA block (as long as you use hollow pushrods) but you can't use LA heads on a Magnum block. For your level of performance either LA or Magnum oiling methods will work fine. The main issue between the two types of heads is more about the strength of the individual rocker pedestals (Magnum, weaker) vs. single rocker shaft that distributes the load over 5 mounting points simultaneously (LA, stronger). Again at your level of power it's also not an issue either will work fine.