Nice work! I just did this combo (water pump, thermostat, engine mount) recently too. Mine had 140,000 miles on it, and the center piece was completely separated from the rubber. I had to pay a shop ($95) to press it in for me. These
double flex ratcheting wrenches came in really handy for me when removing the mount bolts thanks to the extremely long reach and flex head.
Did you have the insert pressed in in a particular orientation? I see that the insert is not symmetric all around. I tried to tell the shop to orient mine just like how a 987 complete mount is, but they did it up side down. Still don't feel any different, don't know if there will be any damage in the long run.
I'm sure you will enjoy the new ride quality just like I do with mine. Didn't know the 986 can be so comfortable (after replacing the engine mount and the rear track arms, of course
)