I am bringing back a 73 2.0L 914. The brakes go to the floor and the car has not moved since 1985 but was running.

Should I have this one rebuilt? or buy the $99 $189 or $350 dollar MC?
Any advice?

Also, I guess, replacing or rebuilding the rest..... any comments on the pressure regulator between the two rear brakes?

they say the proportioning valve between the rear brakes rarely goes bad.

this member sells master cylinders and rebuild calipers.

http://www.pmbperformance.com/page/page/1925563.htm
http://www.pmbperformance.com/calipers.html