have a 440 mild cam with a little porting
auto trans . not a numbers car.. i like Holeys
what carb would you all recommend?
i was thinking 750 vacuum secondary
thanks for any input

Why doesn't anyone ask the OP's level of willingness and ability to 'tune' their new carb BEFORE making a recommendation? A carb that is 'easy' to tune (and needs to be tuned) may not be for them. And most guys are probably wanting a 'bolt on and go' type of deal.

The 3310 is a good universal carb. I have installed quite a few over the years. BUT! They are WAY rich on the cruise. 4 to 6 steps on the mains on most and then, the PVCRs need drilled larger to get the WOT back where it needs to be. And the secondary will need a quicker spring on most every engine I have ever put one on. There are a couple of other things that usually need attention, too. So again, if the OP is comfortable with 'tuning', then the 3310 may be a good choice. But let's be clear; it is putting far too much fuel into the engine at light loads.

And for a street car, the Double Pumpers are even richer. Holley lists them a 'track carb' after all. And for good reason.

If the OP wants a Holley platform carb, I would suggest calling Holley with the details and getting a recommendation from them. They have a lot of carbs with different tunes for different applications. Starting with a carb that is closer to the real needs of the combo is always better than starting father away.

Personally, I would suggest avoiding the AFB/AVS CarterBrocks simply because their 'tunes' are ancient. And if the OP does want to tinker with the idle and off idle tuning, they are a royal PITA. The basic platform is a good one. It's just a shame that after all these years and with all the different companies making a version of them that no one has updated the transitions or made them easier to adjust. But it is what it is.

My go-to carbs the last few years have been the Street Demons. They have the very best off idle transitions going today. Plenty of youtube videos on them. BUT! They are a street carb and are for stock and nearly stock engines. The rougher the idle, the less they make sense.

If the idle is rough, it may be difficult for the OP to get an out-of-the-box carb to get the job done without needing to be tuned or being excessively rich.

Engine like that doesn't need more than 600 cfm but a 750 vac secondary won't hurt anything. The 750 will probably never fully open since that engine will only use 500 to 500 cfm of air at WOT.

Really, 500 cfm? Wonder why the six pack worked so well on the 440, 1350 cfm. They also worked on the 340 engine.

Every B/RB motor, regardless of cubic inches, that I've added cfm on the intake side of the motors made more power at the drag strip and on the engine dyno
Swap 600 CFM carb to a 750, then an 850 and finally a intake and carb change to a 1050 CFM Dominator on a stock bore and stroke 440 bracket motor, jetted for best ET and MPH
Same thing on more than one engine dyno tests, started testing with a 600 CFM carb and ended up with a tunnel ram intake with two 1060 CFM Dominators
Stupid Mopar wedge motors

Simple plug and play Holley 770 Street Avenger

You can't change the air bleeds easily. Check out the Brawler carb I posted BR-67258.