I'd use the dart head, .. good proven part, good power and
you can have them ported later.
I can offer a cnc ported RFD 24* with 2.35" valve and flows 450cfm
for around $3350 complete. Makes easy 1050 hp on 565-582's
http://raceflowdevelopment.com/RFD-h...ock-victor.htm
Curtis