Would this be too much carburetor for a stock Nailhead that only has headers on it? Or would this be more helpful? Maybe this is a race only application? I have a Holley 3310 and was searching for more info over the carburetor when I came across this article: http://www.automedia.com/Building_The_Ultimate_750_Holley_3310/pht200011017h/1 Here's the actual part on Jegs. http://www.jegs.com/i/Proform/778/67101C/10002/-1
I don't know if I buy that much horsepower gain but I have used their main body on Double pumper carburators and they worked just fine. If your unsure whether a 3310 will work on your motor why not just try the carburator as it is now and see how it performs before spending the extra money to buy a new main body. I have also used 3310's on Chevy motors before and they are a good carburator with the vacuum secondaries and easy to tune.
I plan to use the 3310 as it is. I just happened across that and was curious on what improvements or benefits it would have. Thanks.
I may have a 3310 sitting on the bench in a box waiting to be rebuilt. I'll have to check the part number when I get home.