Shadetree mechanics pls advise: transmission/clutch

I going to be replacing my dad's transmission, (got from Volvo Saab Auto Dismantlers in Rancho Cordova), because he has been without 3rd gear for 6 months. Additionally, I will be replacing the clutch, (got from Saab Factory in Santa Clara), as it has been 5 years since it was last done. He has a 1987 900 Turbo 5-speed with 145k miles. Please advise on any TIPS/TRICKS/IDEAS when doing these two installs. I usually work on big american trucks so this will be a bit different for me. The local mechanic wanted over $4000 to do this work. That's more than the blue book on the entire car.

Thanks in advance guys.
Have a happy & safe 4th of July.