welcome!
if there is an another quality option besides webber, I have not seen it.
I ran a webber in my 20/22R engine for many years, and have no complaints. sure, its not going to run at extreme angles, but it is a solid carb. my favorite part about it is, it only uses one or two vacuum hoses. versus the stock million.
on your stock carb, make sure it has a clean filter, and open the bowl, verify the needle and seat are operating properly, and make sure they are clean.
if the carb has never been serviced, this is most likely to put a dent in your progress. also, there will be some sediment in the bowl.
you need to quit worring about the pistons on that engine, and focus on the important stuff. there is nothing wrong with a 22R at 122K