With 615ci pulling on it, I’d go 20 degree no question, if you can stomach the cost of shaft rockers. Brodix BRX is cheapest. Then SR20 is the ported version.

461cfm at 0.600 is 50cfm better than any 24* head.
https://brodix.com/heads-2/big-block.../br-x-series20

The port is high volume at 440cc but the CSA is the same as a 380cc 24* because the 20* port is a longer raised runner.

In 24* stuff, the 0.600” velocity king is this tiny 298cc brodix head, doing 393cfm.

BP RR BB-3 XTRA O
(CNC Combustion Chambers)

although there is some speculation as to whether these really exist.
https://brodix.com/heads-2/big-block...block-series24

The BB-3 XTRA 327 is not fully CNCd so it’s affordable and does 401cfm at 0.600. The ported versions are the same or only slightly better at 0.600”, but pick up a lot at 0.700.

There are some really good small AFR heads too, they really rock down at 0.500” lift. Richard Holdener has tested them if you look back through his youtube.

If you’re staying 24* but stepping up to 0.700” lift the profiler 375 is really bad ass, doing 450cfm.

Im 24*
Build was during Covid lockdown and some parts were hard to get. I already had one set on the shelf so I only had to source one more set. Just throwing this out there for real world reference. Not saying it’s a technically correct build.
Dart pro one heads 325 cc.
Profiler intake’s
Dominator 1050’s
Crane 651’s (.632 lift)
Manley 615 rotating assemblies
Brodix tall deck’s

Dyno’ed 728 hp @ 5400 782 ft lbs @ 4600
Second engine same +/- a couple hp

2.25” intake valve is holding that head back. It’s not very good imo. A porter and a 2.30” intake valve could get you 50hp. I understand the supply issues people are dealing with right now.

Darts owns 335 and 355 CNC program would be a big improvement. I like the rest of your combo. Assuming you run a good full length exhaust in the boat.

Will be interesting to see what happens. As of now I’ve got close to a 355 + - port and 450 @ 700. Cam is 255/259-704/704 net lift SR’s and 1150 two circuit carbs. I could’ve easily went with a cnc head and been happy but it takes business away from a long time friend. Should have a good idea claying up the two intakes for flow bench but still want to see the dyno results and yes the boat being the ultimate. I was he!! bent on going TR but no delivery date in site for any of the 3 I desired. Fked up times all the way around.

If I were to do over I’d probably get the afr 300 cnc oval port and have them fine tuned. I’ve read about some making huge power 540-565 pump gas builds.

Id love to see the boat. DM me or let me know when you’re on the water.

Nice set up. I forgot how many cubes are you running?

I’d be curious how well a set of 4150s would work versus 4500s

I haven't used the 300 cnc's on a motor bigger than a 515 but have almost touched 700 hp using them in conjunction with those edelbrock proflow mini tunnel rams on 2 different 89 octane builds. Id like to dyno a 540 with them, there might be alot of truth to having good signal/velocity vs a big flow number , they work well, where they become "small", IDK yet.

I agree, the AFRs seem to punch above their weight and flow sheet. Definitely something there to the velocity.

What about ported EQ 360cc?
Is there a rule of thumb to avoid overshooting on the volume and ruining the velocity/flow?

I don’t know what that head flows. It would most likely be better. You’ve got a lightweight hot rod but you’ve built Apache motors for it.

As far as rules, I don’t know one.

Cross sectional area is a better reference but they aren’t advertised. Generally I’m just looking at what the smallest head is that flows the most around your valve lift and under.