I had a shop for over forty years and rebuilt many Quadrajets. It sounds to me like the issue could be one of two things; the fuel pump, it's not holding pressure when you shut the truck off. The other common problem with the Q-jets is the well plugs in the bottom of the float bowl are leaking...
Tach
I take it that you have not found a tach yet. I have several, from used inexpensive to brand new Autometer Monster. Email me if you're interested and I can send pics, details: [email protected]. Thanks, Bob.
I have the one off of my '78 Silverado. Not sure where "somewhere" is. I'm in South Florida. Email me for pics, etc.: [email protected]. I won't be available to respond tomorrow; so don't think that I'm ignoring you. Thanks, Bob.
If you still have the factory Vara-jet intake, you won't be able to use a 2-GC carb. on it. The Vara-jet has two different size throttle plates; where as, the 2GC are the same and open together.
Dual Tank Brackets
I stumbled on one yesterday, while looking for something else. It has the plastic shield with it. I know that I have the rest; just have to remember where:shrug:. Getting ready for "Erika" this week-end; I'll keep looking.
LS 4x4 swap stuff.
I have LS Corvette and F-body exhaust manifolds and a couple of oil pans that may work in your truck. Email me for pics, etc.: [email protected]. Thanks, Bob.