"I need to replace the wore out carburetor on my 8N."
Get it rebuilt as Royse suggested. Either GB in MT or my local rebuild shop, AMI.
They do 'mail order' work; give them a call to get a quote & shipping info.
And, they also do brakes, starters, generators, water pumps, clutches, etc.
Automotive Manufacturers Incorporated
2400 N Lombardy St
Richmond, VA 23220
Bushings can be replaced. As to cam wear, did you mic it to determine if its worn or are you guessing?