What parts fit ?

I need a rear master cylinder for a 1979 kz750 twin B4 . I have someone who has an 81 kz750 rear master cylinder but i dont know what years are compatible. I have the one piece rear master cylinder. I know in other models they detached the fluid resevoir . What bike models and years should I look for if salvage yards arent carrying my exact same bike. Thanks all , can post pictures of master cylinder if it will help

The 1981 KZ750 models are 4 cylinder bikes and use a different rear master cylinder than the twins. What is wrong with the one on your bike? If it's not really wrecked it can be rebuilt. Ed

I attepted to rethread the bleeder screw on the top that somehow was already stripped? Needless to say there wasnt much left so It didnt work . Can I helicoil this or maybe just get a bigger bleeder screw? I was wondering what parts fit thinking maybe i could find a cheap replacement. Havnt found one under 75 dollars yet so Repair is my option . I need a screw around 8mm or maybe even bigger. Just lookin at ideas before i mess it up further

So I might be able to get a rear master cylinder really cheap . Only down side is it is the split type from an 80s model. If they didnt change the rod size other than shorten it going into the bottom of the master cylinder, The couldnt I possibly take the push rod out of my master cylinder and insert it into the newer cylinder? Looks like it would bolt on other than the push rod being short. I have access to a welder so I could make a mount for the resevoir .

this is what I want to convert to use on my kz750 twin . Only mine has the longer push rod and the resevoir isnt seperated like this one