Maria-
Sorry , I guess you did specify the "Mr Speedy" chassis....
My advice on the W123: get a number of those 1/4" wobbler socket extensions. Two of the four nuts under the dash that hold the booster to the brake bracket are near impossible without them on a teenie 1/4" drive on a skinny 13mm socket. If you are a petite woman
maybe it won't be so hard to fit in there- otherwise consider removing the driver's seat.
You probably can remove the booster on the W123 without taking the lines off the master cylinder, but be careful not to kink the lines. Let us know how you made out.
Rick