The weight of the engine pushes the engine mount down , so I would say clean up the old ones and refit mate .
Only thing you might find a pain in the back side , are the threads in the mounts and lining them up .
I put a drill bit straight through one side and used a lock nut .
Tip is to disconnect the steering shaft from the top UJ joint just under the clutch fluid pot .
This allows the cross member to drop further down , I undone the bottom arms , so the cross member was free.
Passenger side is easy , but drivers side is a pain .
I sat my 944 on two stands on the chassis legs, some plywood in between. Place a jack under the engine sump , so you can jack up the engine.
If you have access to a two poster ramp ? It is much easier to do .
If you need to replace any bushes on the bottom arms or anti roll bar ? This would be a good time to incorporated into the job in hand.
If you need any support ? You tube is good !! Or ask here as you go along