Fairly sure I have some original unused B40GA clutch springs kicking around in one of the boxes or bits that some day I will never get around to putting together.
From memory they are 4 spring clutches.
Would that be of any use to you for a sample ?
happy to send some over or just do some testing & send you some results.
Like a lot of things I can make springs with the exact same spring rate & free length a hundred different ways

Bike Beesa