If you plan to leave the Holley on the truck, I would suggest a repair kit and thoroughly clean the carburetor.

Kits for the WW are readily available, but do not include bushings; however bushings are also available.

The identification number for the WW (required for a rebuilding kit) is STAMPED (not raised) on the air horn (top casting) of the carburetor. Since this is a GMC, the number should start with 23-

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop