unless you have your CNC indy heads finishe by some one other than indy, they flow somewhere around 510 cfm. Mine were touched up by HRD ( al dixion ) then had a CNC valve job by Joey Grose ( pro stock )now flow 545cfm, my motor was last pulled on a Dyno that is owned by a current pro stock team... made 1282 hp, you can take that to the bank, not 1100, Of course there is more to making up then flow numbers..... The guys that are in my circle are pretty sharp also, and feel that my 604 would make very close to 1300,only pulled it twice in its current configuration , I didn't want to ware it out for a number that means nothing....I absolutely agree with dhemi,there is hp on the table with smaller, less tension rings, bigger carbs , cam exc,exc...just dosnt make cents to have a all out effort n/a mill for a bracket motor......