Not in Sweden, LOL! Nah, seriously, if you choose to fiddle with them, I'd take one out and go to a shop and see if they happen to have any. In my case it didn't take more than 1 size. I can't remember if I had to go larger or smaller. It was around 35 years ago that I was messing with that bike and it still had stock carbs on it. I also had the benefit of having a bunch of mains sitting around which made it seem like a reasonable thing to try since I had exhausted every other possibility.
Are you sure all of your diaphragms are in good shape? When we're talking about carbs this old, there are a lot of ways for them to start going lean with air leaks.
Also, I realize in your original post, you said you cleaned them. I don't know you, and you don't know me either, but there are "cleaned" carbs and then there are carbs that are truly CLEAN. Not trying to be a dick, but it is possible that there may be some stubborn dirt in the pilot circuit. I'm not positive that the MAJ will cause the degree of poor running you mention.
A dirty pilot circuit will (surprisingly) still allow a bike to idle, and once you get past it and up onto the mids, it will run fine again...leaving you with dirty running between idle and midrange...like you're describing.
I've had good luck with acetone getting passages clear and I'll usually squirt alcohol through where the pilot jet screws in to make sure I can see plenty of alcohol coming out of the pilot holes at the spigot, the area where the needle jet goes, and the air jet(s) back at the flange.
Again, not trying to assume what you may or may not know, but I've chased my tail many times until I decided to get real picky and careful about making sure there was clear flow every way I could figure out...and I say this because this is stuff I didn't do the last time I opened the RS 36s on my 87 and only bothered to clear the pilot jet figuring "it'll be fine"😄 I should have taken the extra pains.
If you do choose to use something like acetone, be sure to remove all the rubber items from the carb bodies. I'm sure that is obvious, but again, we don't know each other