In the way of cams, look for a cam with assymetrical lobe shapes, in the 216 @ .050 intake duration range. which should generate an exhaust duration of a little bit more (longer exhaust duration helps with factory exhaust manifolds and such. I checked one of the Comp Cams 268 cams back when they were "the thing" for a good street engine. I had read of their quick open/ slow close lobe shapes but I was NOT prepared for the valve to be at TDC for 10 crank degrees in that mix too. Which means more open time than a stock cam, where max lift only happens for ONE degree of crank rotation. BTAIM
Comp and Lunati have some assymetrical lobe cams now. I'm not against re-ground cams, but to get the additional lift, the base circle of the cam is decreased a bit, as I understand it. THEN also ensure they put OEM-level Parkerizing on the reground cam, too.
With any cyl head from anybody, you might well consider taking them apart for cleaning and touching the valve seats before installation. Mopar Joe has a video comparing two brands of new "in the box" cylinder heads, which verifies why my late machine shop operative always did with new heads. FWIW
The MAIN difference between the 400 and prior 383s is the lowered compression ratio. Cams are not that different, or enough to cause a loss of power from them (basically the old 256/260 4bbl cam, with a few tweaks). USA 400s had electronic ignition standard for the '73 model year, as I recall. Our '72 Newport 400 has it, when it was optional in the later part of that model year. Generally, the 2bbl 383s and 400s had good advance curves (factory specs) which generally allowed about 36 degrees BTDC total, so a little bit more base timing and quicker off-idle timing advance might be all that's needed.
Don't worry about "stall speed" of the stock torque converter. To me, some get too excited about that, by observation. It should be in the 1800rpm range, typically, if it has the 11.75" converter. The alternative would be the 10.75" converter. You can tell from the fluid capacity which one it should have, with the smaller converter taking less fluid, if there are dual capacities listed.
Stall speeds can vary with the amount of power in front of them, with the same converter. With the smaller converter, it might be closer to 2100rpm with the stock cam or thereabouts.
To me, horsepower figures are more about bragging rights at cruise nights than anything else. That horsepower only happens past 4000rpm. Torque moves the vehicle from rest. In this case, a vehicle weighing over 4300lbs (and more with people in it). So, build a "torque motor that rpms" and let the top end power be what it is. Torque also causes the rear tires to loose traction, off-idle.
From my experiences, having an engine which comes off-idle (about 600rpm in "D", hot base idle speed) cleanly and responsive to small throttle inputs makes for a more enjoyable general driving experience, no matter how much power happens past 4000rpm. Certainly, it needs to also eagerly approach 5000rpm as it goes through the gears, too.
What you have now, in that Holley 2245 2bbl, is basically the primary side of a 650cfm 4bbl squarebore carb. How much time do you spend at WOT to need the additional power of the 4bbl? Certainly, the 4bbl might increase power above 3000rpm or so, but with the current gears and general tire size on those cars, that's close to 85mph road speed "at cruise". 75mph with 3.21 gears.
The 4bbl upgrade is easy to do with an AVS2 and related Edelbrock intake. Just also plan on getting the necessary adapters for the throttle hookup and (if needed) the kickdown rod.
Do the rear axle gears last. I like the C-body cars for their extended speed/range cruise performance, but being able to lay rubber counts for a little bit too. There are a lot of smaller 4cys with gazillion-speed automatics that will put every older car to shame in "a contest", so best to not go there! The cars were not specifically designed for that, but in "police mode", they were very credible . . . when they were produced, but not in the current world we now have. But to me, the capability to effortless cruise at 80mph (in current traffic patterns!) is more important than a smokey burnout. Highway fuel economy is important too.
Sorry for the length. Some observations and experiences,
CBODY67
