Help converting back to 10" wheels VBA motor/ VLB frame

I have a 1966 VLB Sprint 150 (Sears model), which has a 1960 VBA 150CC motor installed. The bike would have originally had a 10" rear wheel with a wide 5 bolt pattern. Instead it now has an 8" wheel with a small 4 bolt pattern. My front wheel is still 10". I am wondering if conversion kit # J50015100 will fit this VBA motor and let me go back to a 10" rear wheel. Can the parts for just the rear wheel be purchased separately?

  I also see a GS150 wheel available (# 80180000), which is 10" with a small 4 hole pattern. Does anyone know what the bolt hole spacing is for this rim, and if this wheel could possibly work with my set up?

the 4 stud 10 inch and the 4 stud 8 inch have the same stud pattern ie,pcd. but check for clearence issue,s if non standerd exust is fitted.