When the 80 first was released back in the late 80's and not the early 90's as is often believed, it was not perceived they would be so popular, so as the models progressed so did the options, I am guessing the loom mods were done in batches, perhaps every two or three years? I know a customer who became a good friend and he bought a 1990 80 without AC or leather interior. The AC went in pretty much as expected and the loom was there, and of course her had to change the heater control panel in the middle of the dashboard, his seats which were cloth had no wiring for for anything, no heaters, no movement motors, nothing. He had an electrician wire in the electric powered seats including the heaters. My 1994 has cloth heated seats, and electric lumbar adjustment, I took the drivers seat out to remove the rear heater and rusted pipes and there is no wiring there to power electric leather seats (not in Spain thank you!) It is possible the loom plugs are under the dashboard and you would just need to get the loom extensions? The OP has the entire car so he should be fine, and can soon loop in some parts as he has the skills to do so.
So we know that some vehicles have the wiring looms and some don't, I would think it is fair to say the later models have the more comprehensive looms. It is also true that as a manufacture starts to plan the end of a particular model they load them up with a shed load of options, this is to make the outgoing models more attractive to buyers so the manufacturer does not get stuck holding 'old stock. How you tell one from the other I have no idea unless you get some wiring diagrams and have a look to see what you can glean from them?
Regards
Dave