92 YZ 250 Carburetor Question

So I'm fixing to do a fair amount of work on my old 1992 YZ 250 and a concern that came up is with weather being all over the place in Missouri as well as just getting the bike running better, I want to mess with jetting. Problem is with jetting kits and just finding jets/needles in general, I cannot find anything that dates back to my bike. It has the stock Mikuni TM38 but haven't had luck finding anything for it. I'm new to jetting so my question is, is there jets and needles from a different Mikuni carb that would work for the TM38 or does anyone know where I could find jets and needles for it.

Also, I know that in the mid-nineties, I wanna say the '95 Yamaha switched from Mikuni to Keihin. Quite a few people are swearing by the Keihin's and saying to not even mess with the Mikuni. So would the Keihin PWK work? Any fitment problems with the boot on the airbox? Parts seem way more available for the Keihin so if it would pop right in and I could potentially get better performance, why not do it?

So long story short, does anyone have insight to getting jets for the Mikuni or should I ditch it and go Keihin if it works? If it would work, I'd rather go Keihin. I've got some found for a pretty decent price online.