bikes that have a mechanical (cable) rear caliper

my bike has been converted from drum to hydro disc by the previous owner

although i not happy with the set up the arm on the master cylinder moves on a 45 degree angle instead of in a straight light an there is hardly any travel on the arm making it impossible to bleed the brake if i ever wanted

in my opinion it would be alot more straight forward if i could fit a cable pull caliper (running the cable from the pedal to the caliper with an adjuster to get the tension right)

but the only one i know off is from a sach madass an they are rarer then hens teeth i ve tried using find a part but had no sucess

are there any other cable pull calipers out there?