Sounds like you are fighting a loosing battle. Take my advice and block one carb off till you get the first one running. Then do the second one. You have doubled the problems plus some by adding a new intake. Just one change at a time can drive you nuts, you have three or four going at once. Rebuilt carbs are a problem all by them self!
Vacuum leaks can cause all kinds of problems, and since yours won't idle below a fast idle, I would bet you have one or more leaks.
Even though you have 21", its not at an idle so it doesn't count. Until you can get it down to 600 or 650 steady rpm, the gauge won't tell you much. Even a small leak will cause a big problem with dual or triple carbs, you all ready have 1/2 the air flow through each one so cut that down with a leak and you could be in 1/4 to 1/8 th of the air flow the carb was designed for.
If you can get it started again, leave it at the rpm it wants to run at and spray WD-40 or Carb cleaner around the bases and gaskets, if it rev's up you found your leak.
Joe
