mechanical tacho drive ratio 750/900ss 1993

[jerryz]

is it a 4-l ratio  like earlier bevel drives for mechanical tacho on early 1990s  belt drive engines  pr 5-1,7-1  ?

or can i convert to a  electronic tacho off the coils?  and blank off the mechanical drive on front head    its for a 1991 750ss  that i am cafe racering