Not to high jack this thread, but a Dork down the street put a Holley 600 on his 455 Buick. What a idoit.
Depends on what you want from it. If your GF or kid drives the car sometimes maybe the 600 cfm carb wasn't that bad of a pick.
I switch from Holley to dual Carters / does the motor make more power--too close for me to really say but for sure cold running is much better and it was so nice to be able to go limping home yesterday at 30 mph since somebody drop me off at the shop and I needed to go slow so they could follow me. Motor ran so smooth running on the one 500 Carter.
Then later on I opened it up in 2nd gear and had enough power for around here to pull out in front from way behind.
I dump my headers for factory exhast manifolds-now yes I lost some power but the engine bay is much neater and easier to get to stuff like the starter..plus no more minor exhaust leaks..one leak I did have turn out to be a semi losse header pipe..likely be the last time I need to worry about exhaust leaks for a long long time.
On a side note I have hear for best power even a 850 on a small block makes the most power and a pro carb shop can set it up so low end power is good..just isn't cheap to do. Boosters and metering need to be custom set for the little motor.