Aod......worth the effort?

Don't use any AOD before 1985 - Ford deleted the OD accumulator in 1985 and it was a huge improvement. I would also recommend that you use the internal part from a 4R70w in any performance AOD. It has better gearing and a wider OD band. The clutch drums are steel but they are only formed sheet metal and under high torque they tend to twist. This can be fixed by brazing them solid and then drilling for oil release.
If you are trying for better mileage you will need a rear gear ration of at least 3.5 or your mileage may decrease - especially if you drive aggressively.

 

Paul - He can use his '81 AOD can't he? He just needs to get appropriate modifications to bring it up to date. (YES/NO?) If he already owns it, it may be cheaper than getting a later model AOD. You would know more than I if updating an '81 is possible and is or isn't cost effective given he already owns it. Maybe he hasn't actually acquired this '81 model yet

 

He can use it - it just won't be the strongest AOD. If he plans to abuse it at all it will fail. He could deactivate the servo by putting the spring in the wrong side and there are other things that can be done to make it stronger but no matter what you do you are stuck with the small OD band and the cast clutch drums. (lower capacity)
Running Mercon V and a very large cooler will help more than just about anything else.