Stock heads are what.....130ish cc?
Those are 179cc.
Stock 340/360 under 160cc.
I doubt that’s going to do much to enhance to low speed performance of a mild low cr 318.
But......I’ll tell you right up front.
I’ve never done it (because I don’t believe it’s the right way to go about it).
So...... if the OP goes for it...... maybe I’ll learn something from his taking that course of action.
The other thing is..... are those LAX heads available again?
Not that long ago, they weren’t.