This looks useful for looking for alternate valve springs:
http://www.competitionproducts.com/Valve-Springs-by-Application/departments/2615/
http://www.competitionproducts.com/Valve-Springs-by-Application/departments/2615/
If I said my gold star valve springs that I fitted years ago on the Egli twin were set to 120 lbs would my memory be correct?. I still have my wooden valve spring tester and spring balance I may see what standard springs read..
the Gold Star springs referred to need to be identified by maker and part number before any sensible comment is possible, likewise the beehive springs latterly mentioned. The details released by spring manufacturers permits a reasonable guess as to the possibliity of fitting, but little else.
I get my springs from RD. ......................................
Although I am way down the ladder, I am happy to share anything I have tried.
David