First answer:

Its easier to remove & replace them as a pair, I find anyway.

If its ever going back in you will most likley need to replace - front engine mounts, and the rear transmission mount - replace the engine shocks and bushings while its out - the difference will be noticable. consider having the steering box resealed and replacing the steering linkage at the same time, also check the idler arm bushings - these are all easy jobs when theres nothing in the bay.

Also replace the front pump O ring and sealing ring on the transmission - dime a dozen and they do leak. if your doing this, youll need a new front transmission case gasket since the bellhousing has to be removed.

Somebody else added:

The factory put them in as an assembly, bolted to the subframe, and lowered the body on top if the assembly. That is why the hood does not stand straight up like on a 123 body and all newer ones after that: 201, 126, 124, 129, 210, 140 etc.

All the bodies that do not have a hood that will stand straight up have removeable front subframes.

On your 107 body, it is a bitch getting it out from the top as an assembly. You do not have the pivot room to swivel it up and out without the crank pulley nailing the radiator [or the A/C condensor if you have the radiator out].