The Holley on the 396-325hp is a 600cfm carb. The Qjet is by far the best choice of the two carb-manifold choices. The intake is cast iron for both the Holley and Rochester carbs.
The '65 big car is not available with a 396-375hp engine. That was a Chevelle only combination. The full sized car and the Corvette were available with the 396-425hp engine that shares much the same specifications as the later 396-375hp engines, including the NHRA power rating. The '65 engine has slightly less camshaft lift (497/503 vs 520/520) than the later engines, so that must be taken into consideration.
You need to go here:
http://www.nhra.com/tech_specs/engin...ts/CHEV-65.rtf
Get familiar with all those specifications because that will answer a lot of your questions.
You will not be able to get the car to 3442 lbs with an iron head big block and a driver.