What is your goal?
Hughes Engines has CNC versions that flow about 400 cfm.
I would look at getting paired rocker, rocker arms that replace the shaft type rocker arms, if your going to have more than 700 pound open spring pressures.
It takes a bit of work to get a 2.00" install height valve spring to fit with the stock valve lengths. I don't know anyone who has used longer valves yet, but might be an option if going to a custom or semi-custom rocker arm setup?
If valve spring pressures and valve lift are not too high, then the T&D offset shaft rocker arms work good using ARP rocker shaft studs.

Anyone using the Trick Flow 270's?