[AZKen]

I don't understand why you are messing around with meter bodies? Are you trying to save this carb because it is somehow numbers correct for 1960? What section of the carb is this number? You have not been able to find a 1960 1904? You are obsessed with metering bodies. How do you know that the lack of performance is the meter body. The word "pro" you are using means nothing. Many here are unsung pros also. This is where 6066 GMC pros live.
There is no one on earth that will care if you use a different 305 V6 GMC manifold with a WW carb. The manifolds look basically the same under the air cleaner. The truck won't be worth one penny more or less. No judge or buyer will ever have that knowledge that 1960 305A had 1904 1BBL but a 1960 305C had a WW. You are too tight on this. Maybe you are an expert on 1904, that's great. I'm not. I don't think you need to be this rigid. If you want me to find a specific carb out here in my area, give me the numbers and I will try to find one. It seems like the answer is obvious. They only metering body that will work for you is one from a carb like the one you were using when the truck ran good.
You are stuck on a carb that you say is crappy, they all leak, problematic, warp, no fix, can't find metering body.

Search data:

The Holley 1904 was prone to warpage of the main casting and the bowl, similar to the Rochester B. Since the bowl mounts vertically on to the main body on the 1904, warpage causes a fuel leak at the bottom of the bowl.

The earliest 1904's had the problem, but it took longer as the bowl was glass, which didn't warp. When the glass bowls were replaced with die-cast bowls approximately 1959 or so, the problem got worse, as the die-cast bowls also warped.

The Holley 1904 is available in two different flange sizes (like the Rochester B) and several different internal venturi sizes for use on engines from 144 to 305 CID; and used ones (except the ones for the 144) are much more common than even the Rochester B. The warpage is much easier to straighten than the Rochester, as there are no projections on the surface to straighten.

The flange is SAE No. 3, 2-15/16, I believe there are Carters and Rochester's that fit. When buying a replacement donor carb, the rule of thumb is get it from a motor within plus or minus 3 per cent Cu In of the receiving motor.