New carbs are indeed the answer....IF you don't care about originality in judging.
For those of us who seek authenticity in restorations, the original carbs - with the factory stamps on the carb bodies - are the ones we want on those bikes.
That's why we ask eBay
sellers "What are the numbers stamped into the mounting flange?"
Those numbers will tell us what make, year and model of bike the carb was originally on.
In the case of Concentrics
, those numbers are the tiny ones stamped into that lozenge-shaped raised area on the side of the carb body.
This is why we are willing to spend what it costs to re-sleeve the old carbs.