Carb info

Hey anyone know what stock 429 scj Holley carb came with vacuum secondary or mechanical I ask because it came with a 780 and I have mine in a 79 4x4 and have to go with vacuum And mine is bored .30 over bigger cam 563 int 583 exhaust roller rockers and I don't want to over carb or under carb it and I'm stuck between Holley 770 ultra street avenger and QF 850 and I ask about stock carb because if it was mechanical ill go with the 770 if it was vacuum ill go with the 850 QF any advise will be taken I'm not one to post for advise and already have my mine set and try to get someone to agree with me any help will be taken to heart thanks
Oh yea duration @ .050" int/exh 246/256

Why do you have to go with a Vac secondary carb?

A 850DP would work fine, but if you want to run a vac carb the QF 850 would be a good choice. I'm not a big fan of the avenger series of holleys.

I have read and thought that if your over 3000lb and had an automatic that vacuum was what you had to run so to get all that weight moving have the vacuum a chance to catch up as with a DP it might flood before the motor could use all the fuel the DP WAS supplying

On that truck ,on the street you don't NEED a dp.I like the vac sec for that . But like said,i'm not a fan of the avenger series either.

I kind of thought so I've had a 750 vacuum for years but always thought it could use a little more carb that's why I asked about 770 vs 850 I pull in super stock class and 4 barrel and headers is about it they don't know it's a 429scj when asked I just say its BBF And no one says anything so I keep running I'm not the only one I know there are some guys with big vavle DOVE heads as well but I Usually get em on RPMS most of the time I think ill drop the cash in QF 850 vacuum adv. is red the only Color they have

I owned a 429 SCJ back in the 70's and when I got it had 28,000 miles on it and it was stock and it had a 780cfm vac. secondary Holley from factory. That said I switched to a 850 double pump carb and with just some jet changes and a carb spacer it woke the SCJ up! It was under carbed from the factory. In fact in the old Ford Muscle Parts program that was the first up grade was to install an 850 cfm carb.

Thanks for the input And the fact that you were around back then and have first hand Knowledge I grew up driving in the 80's and they didn't make 3 HP between the big 3 auto makers and as kids we were hitting every junkyard we could find looking for pre 72 motors back then I could out run most anything with my truck not the case today with all the aftermarket stuff out there but I still like to try and make my HP with junkyard finds and know how any way thanks for the advice guys and remember drive it like you stoled it cheers