Want an automatic??? You will loose any sence of performance IMO.

Ok.... I might be in error in a few places as this is going back a bit...and in reverse order of what was done... What was done was remove the auto for a stick.

Raise the car on 4 stands, Disconnect the battery, remove the shifter and boot.
Dive under the car and drop the drive shaft after you take a measurement as it might well be a different length from the auto one.
The crossmember is the same but note the holes in the sub frame have extra holes in the event you need to move the crossmember.

This should drop the tranny angle for a better access to the top bolts. Drop the inspection cover, the starter, Undo the clutch cable, speedo cable and the tranny.. I never bothered with a jack to get the tranny down and just dropped it on my chest. (At one time I commonly replaced a clutch in 45 minutes total)

Remove the clutch pressure plate, disk, and flywheel. Replace the rear main oil seal. Install the flex plate and auto tranny. Check the cooling lines if any, and the vac pod if any... (I simply forget) If any of that exists then you will need to add a oil cooler and what ever vacuum tubing you need or the tranny won't shift.

Install the crossmember and drive shaft. Install the shifter inside, and pull the carpet back and place the clutch pedal under it... (Beats installing a clutch pedal for sure, and leaves the option to go back to stick..

Add ATF connect the battery and send yerself a card sayin' Welcome to the world of the slush box!... Yuck... Take it for a test drive and see if the speedo reads anywhere near right. If not find a different gear for the tranny, or convert to tape on the dash (home made conversion chart)

As for old age I will be 52 soon and pray I never get as old as you are now! Mac