Hey Beeno. Cool 90!

The #6 plug is tricky, when I do it I drop the sockets into the hole one by one and use 2 short extensions if I remember correctly. Just push them together in the hole to click them together and do it in reverse to get them out.
Getting the motor out, after you disconnect the loom, hoses, tailshaft etc and removed the radiator. If the 90 has the fold back bonnet like the 75 do that and put the rear of the car on jack stands. Then start lifting and find someone to lie under the car to steer the extension housing out through the tunnel.
Cheers, Scott