Very Nice!

You have a few projects:

".. except for the stop light." Maybe, if all of the planets in the universe line up, you just need a bulb and you can get the old one out. The brake light switch on the back of the master cylinder is as easy a fix as there usually is - no need to bleed brakes unless someone "helps" by stepping on the brake pedal you while you have the old switch out.

"Horn doesn't work.." One terminal on the horn is always hot so you can honk even if the key is off. Find the hot side, ground the other side and if it hoots, you get to chase the wires and switch up through the steering column. If it doesn't, it's not hard to take apart and clean the contacts. There is a contact adjustment on some versions that can get screwed in too far or backed out too much.

"., no heater.." Physically no heater, or no blower motor? The motor is a simple DC motor - brushes and bushings are very common issues. It will come apart with some persuading, but finding brushes can be a bit of a challenge.

".. and the windshield wipers don't work. " It could be the wiper motor itself, or you could have lost the vacuum boost section of the fuel pump - or even both! Mr. Google has advice on trying to fix a TRICO vacuum motor - some of them even work.