I found a good deal on a rebuilt Holley 850cfm Double pumper for $200. I have a 580-600hp 468 but i'm using the stock auto and rear for now. I do plan on getting a 4L80 trans with 3000 stall hopefully by summer but will still use the 3.08 posi rear for a little. I know you can run DP's with manuals or auto's with high stall converters and low gears. Do you think the DP would be ok when i get the 4L80 with 3000 stall but still use my 3.08 rear for a little?

 

The 850 should be a good choice for a 468, with just about any tranny.

 

i heard that double pumpers bog down with an auto trans with stock converter and high gears..

 

DP carbs don't bog down because of any particular trans or gearing, unless there's some other issue that also contributes to that situation. An engine that builds very little low end torque or power will bog with a big carb that's got mechanical secondaries.
If your engine falls into that categorie, then it may be an issue. I doubt it, as an 850cfm on a 468 cube engine will not overcarburate it, unless your cam is designed for mid to high end operation. If that's your cam, then you definitely need a vacuum secondary carb, but I'd still go 850cfm with that size engine.

 

my cam builds power from 2500-6500rpms. does that qualify for a vacuum secondary carb?

 

I think you'll be fine. I have always preferred a dp. Most vac secondaries don't have metering blocks with jets. They have that plate deal, you can get different plates but I haven't ever seen anyone try. On the hand they can be converted with a traditional block and a plug for the power valve. DPs come this way from the factory and give you the ability to tune primary and secondary with the same $50 box of jets.