Contact YS parts and Service regarding parts for these old engines. They probably have some. I'm not as familiar with the parts as the 4 strokes. Its beena really long time like 1989 since I worked with a YS60
Back then I wasn't as experienced with engiens as I am today and I guess 17-18 years of memory seems to fade into the distance. Richard and crew often do work on the old engines and he has a cross reference of the the parts.
www.yspartsandservice.com
Be patient, it sbest to callm but they are fairly busy this time of year.
Troy Newman
Team YS