Suggestions for new design Aluminum Mopar SB clean slate (kind of) cylinder heads

I have not read through all the responses here but something similar to an RHS/Indy-X head (which are Magnum based) in aluminum would be a real good starting point. Minimum 2.02" valves with options for larger ones and like PRH said larger diameter spring pockets. Dual exhaust pattern for larger W2-style headers would be good too so you're not limited to 1 5/8 primary tubes. Maybe consult B3 Racing and have him help you design in closer-to-optimal rocker geometry. Make sure there is sufficient material to enlarge the pushrod holes if needed. Thicker decks too for milling. Come up with a CNC program for 300cfm and they'd sell.