All of that is pretty standard for vintage JBLs. Grills are usually missing (discarded when they invariably break or rot), so simply "shot" at least gives you a template to work from. The torn mid is also not unusual and an easy fix. Depending on how bad it is, you can simply use thinned Aileens and an artists brush or if it's bad, use a piece of coffee filter paper from behind and the thinned Aileens. Think of the Aileens as Bondo and the filter as sheeting. You want to add as little mass to the cone as you can get away with. Mids don't have much excursion, so you are really only concerned with eliminating any possible paper buzz at the tear. As for the cabinets, JBL was generous with the thickness of their veneers, so they tend to be easier to work on that most. If your tweeters aren't pushed in, you've avoided the biggest headache in restoring a legacy JBL speaker.