I'd be cautious about taking a 1,000 mile trip in ANY car I just purchased - even a brand new car (though, I guess I'd feel pretty comfortable if it was a quality car...). If you buy a used car, chances are it needs work - stuff that you don't notice on the test drive, or stuff that develops during the next couple hundred miles - perhaps something was fixed "quickly" and not properly. Or perhaps it's a new ailment. Either way - it's a crapshoot.
When I bought my Firebird, I drove it 120 miles back to my house. Luckily, I had no problems. And also, within 100 miles, I'd get free towing back to my place with AAA if I broke down - PLUS I had my wife in the "chase car" just in case as well, along with having my cell phone on me. Can't say I wasn't a little nervous about the drive - even though I had test driven the car, and had a mechanic inspect it before driving it home.
Now that I've had my car a while... uh, I now have reason to be nervous on a 120 mile trip! Hahaha - before it was fear of the unknown. Now it's fear of the known! hahahaha
'68 Firebird, 350-4, 2 spd auto, triple black, Dlx Interior