We put a new booster off a 84 300TD and put it on a 80 240 d .

did not take the master off either. I did not want to do a brakle bleed session. If its just the booster and your master is not leaking .. I'd go for just the booster. .. and yes it will fit.
Just bent it down(master cylinder) and removed the old booster and replaced with the good 300td booster.
Hardest part was the 4 bolts on the interior firewall... gear wrenches made that easier as well.

__________________
81' 240d 4 spd 140k on the clock