Took me 15 Minutes on my sons 1980 AMX.
Lower the engine and trans in as close as you can and have the engine as level as you can.
Helps to have a jack under the tranny bell housing to keep the tranny level
Get under the car and un bolt the motor mounts from the engine block.(3 bolts each).
You may have to lift the engine slightly to get the motor mounts to drop into the engine crossmember.
Once you have the engine mounts in the cradle , attach 1 nut loosely on the bottom of the rubber mount to hold them in the cradle.
Now lower the engine down onto the mount and wiggle the engine so you can bolt the metal mount to the block.
Only install the bolts loosely until you get all 6 installed and then drop the engine in place.
Don’t forget the body ground to engine mount on the passenger side as I did.
This has worked well on eight V8 installs.
I never had to worry about paint on the fire wall before but removing the valve covers is a good idea.
I would also remove the wiper motor assemble.
Hope this helps.
Bryan