Neighbor who owns a shop down in the City of Chicago recommended this company and sends all his carb work out to this company.
https://www.uremcoinc.com/
I was having trouble with my GTO last year with hard starting after sitting for just a couple of days. I pulled the carb and had my neighbor take it and send it off to UREMCO.
The cost was $335 for the rebuild plus another $40 for S&H
By the way it is not a REMANUFACTURER CARBURETOR. That is just the box they package it in.
Results after rebuild and installed. Few light pumps of pedal and one full push to set choke and GTO fires up are after seconds.