Did you measure the runners after the full cnc porting? I understand what you're saying about port velocity but I've also seen several examples of 305-315 make plenty of power over a wide range of rpm. Mercruiser used 319 cc rect ports on 365's seemed to have enough velocity for that.

Good point Jamie. No, I did not. Just going by what AFR classifies them as. The point I was trying to make was I don't think I left any power on the table by using oval port vs rectangular port.

If you talk to the guys that are at the top of there game in cylinder head design they will tell you that an oval port being the same size as a rectangle will have more air speed and therefore fill the cylinder better and make more power.

I don't think you can go wrong with either Dart or AFR's you will make good power with either ... just depends on alot of other factors that will make the difference JMO .

Go Pro comp or go home!

Valvetrain geometry is a pain in the azz on darts, I've had much better results with afr's. The darts are still great at making power.

Post #15 DERAIL !!!! lol

I may have missed it, 502 MPI, EFI, or carb, a restricted plenum and TB will also be a determinating factor to runner size. JMO, also depends on the budget, I don't think you can get a full CNC'd Brodix, Dart, for the same price as the AFR's

Bang for the buck, AFR 305 with CNC chamber option. If you are seeking max effort, and don't mind spending the extra dough, the full CNC 315 version would be my choice.

Darts full CNC 335 is a nice head as well, but not cheap. I'm not too up to date on the brodix stuff, although their big ovals seem pretty bad azz too.

It sounds like what ever you do you better get the rite heads for the 540 cuz its going to happen if you are thinking about it now. I am on my 4th set of bigger heads for the same 2 engines in my apache. 1pair-312cc 2pair-351cc 3pair-383cc 4pair-415cc All Brodix
My first set where to small motors were turds. Second set ran very good.
Hope I helped your addiction! Don't build a turd!:daz: