CB750F1 rear master cylinder issues

[Daren]

Hoping someone can help. To save money I cleaned and reassembled my rear master cylinder rather than rebuild it. But I do have a very, very slow leak.
As owners of the F1 know the rebuild kit for the rear master cylinder is almost unobtanium and expensive when found.
Almost $90 on ebay. Does anyone have a lead on one which is reasonable?
It may be cheaper to refit a used 1980 or 81 master cylinder to a custom mounting plate as those kits are still available and cheap.
Has anyone come up with a solution for theirs?

I tried to search this topic but didn't find anything, maybe I searched the wrong keywords.
Appreciate any assistance.
cheers.

 

[Daren]

An update for any who might be interested. Research may have solved the problem.
Apparently the GL1000's from 1975 thru 1976 used the same rebuild kit as the F1 and available for 1/2 price.
so I ordered one and will let you know if it works. Otherwise it will have to be a custom fit of a generic master cylinder.

 

[Daren]

Good news, it does fit, they are the same, readily available and cheaper.