Not surprised. I should buy them all from you.
I emailed several vendors who specifically deal in Mikuni carburetors. (Canada never replied)
This was one response which was repeated by others.
~Unfortunately for you they slides are
very unique to that bike and while they are available for CMSNL they are
crazy expensive...
Thos same carbs were used on hundreds of models across the big 4 Japanese
manufacturers from singles to 4 cylinder bikes. But while they may look the
same on the outside the insides are VERY specific and wildly different so
parts from one BS34SS won't fit another, they are very model specific,
particularity the slides...
Chris