The 750 DP is one of the best carbs ever made. with a 3000 stall just try it. A 600 is probably too small for all out peformance but you can try it? don't over think anything till you drive and make some runs. Big first items is make sure you have your distributor re curved with light springs right from the get go.Set total mechanical advance to 35 or 36 and don't hook up vacuum advance for a couple three weeks (if ever it's a crude cruise gas mileage device designed in a time we had way different fuels than now) If you must try the vacuum advance make sure it is on ported vacuum and not manifold it SHOULD NOT affect idle when you plug or unplug it.
Have some fun