Early/Late Carb and Plenum Matching

[wall-of-death]

Hi,
I have a 75 gl1000. I bought it without a carb and many other parts and so bought the first gl1000 carb I could find for cheap just to see if I can get it running/what shape the engine is in (if it's ok, planning to get the correct carbs eventually).

I bought a late model 771A set which I heard "would fit" and figured I could up the main jet sizing to compensate for how they're designed for a shorter intake valve duration, and that would get me sort of close to matching.

What I didn't expect was the accelerator pump on top of the plenum was not there on the early carbs, and so it will not fit in the frame (easily, without signifigant disassembly during installation).

I found a set of 755A carbs on ebay, but they have this same pump on the plenum, whereas other reference pics of the 75/76 carb plenum don't have it at all. So I'm wondering if someone could have switched the plenum that has the pump onto the set of early carbs to improve acceleration... and if that's not an inane thing to do, would it be worth it to maybe buy that set (since its not super pricey) and deal with the struggle to install them anyway? Is that something that people do - swap the plenums??

[wall-of-death]

To add...

Reference "GL1000" carb without pump on top: download/file.php?id=851

Reference "755A" photo WITH pump (top right of plenum):

https://www.picclickimg.com/d/l400/pict ... -carbs.jpg

Allegedly, these are both 755a carb sets.

Is the one on top just missing the pump piece? Am I missing something in how to install these? I have the Clymer manual which says to remove the top cylinder covers for clearance but I'm still not able to sneak it in.

[Maz]

The "pump" you are referring to is the auto enrichment valve, which richens the mixture on deceleration to prevent popping, backfiring on the overrun. I find it easier to remove the top or the whole thing (2 screws) before fitting the carbs, then refit it once they are in place.
Maz