3/4 MC piston

Does anyone out there have a single or pair of 3/4 inch master 
cylinder piston(s) from the early Spridget disc brake systems? Turns 
out the ones I have are not the original design and I need at least 
one as a reference as I'm still working on getting these reproduced. 
I can return it if you need it back.

Comprehensive photos with specs would be a good alternative if I 
strike out on getting one.

Thanks.