[My427stang]

I ran a couple of those, last one was on a 67 FB with a 410.

The best street/strip setup I have seen is to run 2 450 Holleys, and go with one size larger squirter. The manifolds like a little extra shot for the long runners and with the 450's the flow starts quick enough it doesnt need the shot to last long

To get them balanced, start by adjusting your idle on the bench with a feeler gauge behind the plate to make them the same. Set the a/f to 1 1/8 out then if it doesnt idle, be very careful to add the same amount of turns on the idle setting on each carb. Think of it as two 4 cyl motors that have to be idling at exactly the same speed

Once it idles, I set both idle a/f mixtures at highest idle / vacuum, then finish the idle adjustment by checking vacuum on each carb and adjusting idle speed

Its a great manifold, sort of runs out of breath at 6000, but man it makes some decent torque. A good single plane will run circles around it above 5500, but once you get it dialed in, it'll run strong and be plenty happy on the street. It wont be less streetable if you stay with 450's with mechanical sec, but with 600's with vac secondaries, its harder to keep them opening together and the bigger carbs dont get as good of a signal at idle/transition. Bolt on the 450's and you'll have a blast