LA318 Edelbrock Magnum v RHS LAX Heads

2.02 + 1.60 = 3.62 - 3.91= .29. Space between the valve is smaller than the .29. Much!
Valve shrouding is the least of your issue. Other companies don't mind it and there set ups are extremely shrouded by compare. But you have none to talk about.

Velocity? The next biggest non issue you have.

The choice is up to you. You all ready wrote out the pro's and con's to the heads. Price is all that is left to figure out.