Hy panman, I have found a "corvette" master cylinder which has a 1 1/8" bore, Raybestos p/n MC39018 if you wanted to use this master cylinder with drum brakes you would have to install 10 p.s.i. residual pressure valves in the ports which feed drum brakes. If at some time in the future you would like to "upgrade" to disc brakes, you could simply remove the residual pressure valve from the circuit feeding the disc brakes, and plumb the line directly from the master cylinder to the calipers, hope that helps.
