Factory Magnum Heads

340,
I use a superflow flow bench and use 28".
As for the stud bump in the port, you can remove alot of it but the more you remove the weaker the stud or rocker bolt support will be so I left most of it in there and I thinned the pushrod pinch as much as you can and still have material there. It's actually thinner at the bottom of the port than it is at the top, so be careful not to cut through or the head will have to be welded up. If you look at the flow #'s most people wont use a cam in the .600 lift range and use this type of head, so you only have a 7 cfm gain at .500 lift from the gasket matching and the lower lift flows arent as good so if your going to use a cam smaller than .600 lift I wouldnt gasket match the heads. The trade off isnt worth it. The velocity was better before gasket matching, but you just dont know unless you try something new.
So in this case the pushrod pinch area was helpful and removing any of it actually hurt the low lift flows, where the bowl made gains the pinch area took them away, so unless you have to have these heads for class rules or some other reason and custom ground cams in the size of the max flow at .600 lift then I would use a different head or run a smaller cam. Your combination dependant. But for the street these heads would be a very good choice for lifts under .500 lift and some mild porting being done.