I don't know how much a Magnum head can handle as far as lift is concerned in stock or worked over form. As cast, be it Magnum or LA head, once the porter takes over, it is all a wash on what is better or not since the combo of the engine and intended purpose of the engine and what the builder takes advantage of is another story.
IF I was to do another iron headed engine, it would be one of two ways.
Dead stock/very mild hop up or a W2 to go make some power with. That's it.
Glideriders build meets mild hop up. With or without porting the iron. It's on track to be a nice power plant.
