Nash, I have never ran my stock Milani under #60,. After a zen pipe it's in the high 60's. There is no way 75cc kit should be running optimally in the 50s range. The cylinder size has increased by 25cc's, which definitely calls for a larger jet. I still say upjet this bad boy.
But honestly, I wouldn't do anything at all until I got a pipe for it. You are just going to have to do this all over again.