For instance if you want 275+ cfm w/2.08 out of ANY of them , you have to lay that short turn WAY back, further than the entry level guy would feel comfortable with. Another int port like that is the slant six, a lot of guys don't know what to do with those to get in the 190's w/1.70 even.
Work the 516 ex to the larger valve with seats, open bowls and blend to runner size, straight up from the seat on the exh short side and just roll the top to the floor where it straightens. I bet thats clear as a bell, right? Would have to show you.