Probably in the wrong section but on my old 427 oval port over cammed 10-1 motor,i ran a 12.501 with not enouh converter. Now im doing a new build and have 2 options now:

i bought a set of older merlin rectangular ports for 650 fresh, they are 310 cc, with 2.19/1.88s, there 89' models, talked to the rep at world products and he said they flow 320cfm at .600"... sooo
i bought a 7416 casting 4" stroke crank
i also bought an eagle cast steel 4.250" crank, i bought eagle h beams 6.385"
i found bench flow numbers pretty comparible to these, which were merlin 310cc heads but had 2.25 valves, but on desktop dyno, the 468 made approx 20 ft/lbs less than the 496, but the horsepower was down by 15 to the 496, BUT the 468 had more torque past 5000rpms... and hp equaled out...
im prob gonna run the same cam, .660/.666 254/260* @.050.....

im going to buy my pisotns in the morning, any help would be appreciated.
just trying to get some 11.00s on pump gas.

 

no replacement for bigger displacement, it'll make more power in lower rpms, which is better on valvetrain and engine components.

 

how heavy is this car? and what kind of tires?

 

3600, and most likely always be 275/60/15 dr's

 

496ci! That could very make 600hp with those heads and that cam. It oughtta be a pretty good combo. If you got the crank and rods, then there is no question as to what you should do...Buy some 496ci pistons!

 

I don't think you're going to run enough rpm to utilize the rectangular port heads. Higher stall converter and gears will be required. That's also a very small cam for a large BBC.

I run 310 Canfield heads on my 540. They're a little small for the engine but they produce enough power for the ET I want to run.

 

I also think the heads are to big. Do a 496ci with a ported set of 041 big oval heads you will go faster. I put a 454 together for a friends 71 chevelle with a soild flat tapet cam 3.73 gear 28inch tall tire 2500 stall 3800 lbs car ran 11.70s on 87 oct gas.