I recently installed a new master cylinder. I have boosters and wanted the 7/8” bore master cylinder. I found the one shown In the photo. It is from a 1983-1986 Dodge Ram 50, Dodge Challenger and Plymouth Arrow, as well as a number of other cars of the era. I bought it at Autozone for $39 and it was in stock! I removed the two pressure valves in the master cylinder, since my remote reservoirs are the highest point of the brake System. The ports are m10x1 so you need to buy the correct fittings for the 3/16 brake line. The ports are on top. Another cylinder I considered is from a 1974 Mazda RX4. This appears to be the same as the previous part but the outlet ports are on the correct side, so the plumbing is easier. I could not find one of these in stock, but Rock Auto now has a Raybestos MC39251 in stock for $82.79. You will need remote cylinders for both of these master cylinders.