I have slow and faster wipers but, even the fast setting is slow as all get out. Where should I start?

Could be you have bad grounds. Particularly if the car sat for a long period. I think if you go to Jeff Bowlsby's site he has a list of all the grounds on the car. They should be cleaned up on 40+ year old car.

If that's not it, a fubar motor?

I would do that and lube the linkage with PB Blaster.

Could be dirt and old grease in the linkage. It's a pain to get to, so it's worth cleaning up the electrical connections first. Could also be the wiper motor going out.

--DD