Interesting. Rare but not overly valuable. I wonder what the Marti report says about it. Likely a plain jane coupe. Oh, and, don't rule out that the owners manual can be put into any other 67 Mustang glove box. Does it have a VIN number on it? or Unit number?
The car is likely terrible to drive because it's worn out and/or needs maintenance, not because the existing equipment itself is terrible. I always give this advice, although it seems like no one ever takes it since it's sexier to just buy a boatload of parts- get the car you have working properly before you decide to modify it. Have a plan and a reason for the mods you choose (rack and pinion? What's your cost-benefit on that one?).
In proper operating condition, these are fine cars to drive bone stock, just as they were back in the '60s. Modified cars that are poorly sorted drive like crap, too.