This is a case, where, like I said, the best choice is the 310 Canfield. I have built at least 20 big blocks in the last 5 years, as small as 461, and as big as 509, with these heads. If there is a roller cam involved, then the bigger head works best. I am a big fan of oval port heads for street engines and mild bracket engines, but, when you want the best of both worlds, even on 461 cunic inch, these heads work. 700hp is easy to make, with nearly 600 ft/ls even on a 461 10:1 pump gas engine. Bottom 10's at over 130, in a 3960 lb, all steel 70 Chevelle, stock suspension street car, with only 461 cubes, on pump gas, is plain fast. Don;t care what anyone says. Make it a 496 or a 509, and take 400-500 lbs out of the equation, and its a legit, real 9 second all motor pump gas combo, that is very street driveable.
To put that into perspective, that 496 combo, makes more power than gm's 572 engine, with a smaller cam, and not a dominator, on pump gas. Granted, the 572 inson't maxxed out, but neither is the 496/509
Like I said, the Canfields are the best deal out there. The heads for above, are in the $2000-$2200 ball park, ready to bolt on, depending on final configuration, and the parts used. Mainly valve springs, and they can vary but a lot in price, depending on which ones you use, and also if titaniumn retainers are used or not. Thats quality valves, ARP studs, comp guidplates, roller springs, custom valve job and guides sized, and some porting. They flow in the middle 360 to low 370 range on the intake, and 300 on the exhaust. And, at a later date, additional porting, will make them work well on 540-565 inch engines. I have made well over 900hp with the 310's worked hard, with a 2.30 intake, on the 540's-565's. Ports about 330cc, and over 400cfm. Its a great head thats very flexible, that works.
Frank
Advanced Performance
www.get-ap.com