1 5/8 would work, and those are most common for a classic stang, but a 1 3/4 would be better if you can find them.

 

header should be invested asap. but why dont you leave the carb and see how it runs first. take it to the track and see what it lays down. i think 700 seems right.

ihave a 650 that im not using that a friend gave tome because it was too radical on his 350 camaro.

 

I meant to say that if you run a Demon carb, just remember that they flow way more than advertised because they are wet flow tested where as Edelbrock and Holley carbs are air flow tested. For example, my 650 Demon flows roughly 725 CFM of air, but it is advertised as a 650. On top end at maybe 6500 RPMs you should be making around 500 at the crank. Be sure to put a billet servo, good valve body, and really good clutches/bands in the C4, otherwise, it will take a **** on you whithin the first couple hundred miles.

 

I'd run a 750 carb or a mighty demon 750 annular, 1 5/8 min on headers if not 1 3/4, I'd say hp should be around 430-445 at about 6000 rpm.

 

So do you guys think i can lay down 12 second on d/r's? with a 3350lb with a c-4 and 3.89

 

Ok, I just plugged it into my new Virtual dyno and...
463 HP @ 5250 RPM
523 TQ @ 3000 RPM

You didn't specify which intake, so I just put in a dual plane.

I'd say that should be close.

Too bad you cant get a Hyd. Roller cam with specs close to that. It would jump to 544 Hp and 554 Torque.

By the way, those numbers are with a good port job and a high flow exhaust.
As it is, it ends up being 360 HP and 370 Torque. [&:]

 

you will be ok with your 700, but i would probably look at a 750 demon....but you really need to open up your exhaust with some real headers and a 2.5 2.75 in exhaust

 

well I have 2.5 inch exhaust from pypes performance all manderal bent with x-pipeso all I need now is a nice set of headers