As for the Holley carb, here's a suggestion:
Contact Holley Mf'g customer service department ,direct.
Here's my story. My 1987 Tioga Class C motorhome is on a Ford E-350 chassis. I bought the rig from the original owner.
Ford 460 engine, w/ Holley 4BBL, made for Ford.
Anyhow it was a always a terrible gutless wonder. Had to floor it even on the most modest hills.
No mechanics locally wanted to work on the carb.
I contacted Holley (this was in 2000, BTW ) and they have a service to "re-manufacture", not just replace with a parts kit, most carbs.
So I'd guess they have the parts for your carb too.
I sent the carb to them , they went thru it, found wrong jets, power valve not working, vacuum secondaries not working, and re-bushed the throttle and choke shafts. Made some other production upgrades.
They also flow-bench tested it for proper operation.
I got it back in two weeks, and they said it the only thing I might have to do was adjust the idle speed.
(Did that.) Huge improvement in driveability!
The bill was $302.00. Heck I could have spent $200 + locally and not had as good a repair job.
But you should call Holley regardless to see if they have the parts you need.
My $1.98. $0.02 doesn't buy anything with inflation.