rear calliper for 81 z500b3 help

Picked up an 81, z500b3 project the other day and have noticed that it seems to be missing the rear calliper. Is there a known replacement and or upgrade for this part? Struggling to find information. Can I use any rear brake calliper rated to 500+ cc ?

Any help would be appreciated!

I think your bike uses the same caliper as the 750/4 from '81-'83.

I know the caliper brackets are different, i think it is the same casting but the smaller diameter axle on the 500 uses a bush and other models like the 1100 has the axle hole offfset to compensate for the larger disc.

If you want to mix and match you could, with the appropriate rear carrier, use pretty much any 7 hole disc between 260 and 270mm. I would go for the minimum as the rear discs are rather too powerful anyway imo...also reducing unsprung weight and rotational inertia is always the aim.

You can even use a left or right front caliper, , just the banjo asnd bleed will be in different places.