I'm buying a Mustang Convertible....

[Hozer 88GTConv]

IMO, you can't go wrong with a 88-93 Fox Body.
They are cheap to buy a maintain.
If you go crazy with mods, it's still cheaper than most new cars and you really learn a lot about your car.
I got my convertible when my Dad died.
He said in his will to "drive it till the wheels come off"
I never knew anything about 5.0's, much less EFI's, etc...
Now, in 4 short years, I have built the engine myself(didn't need to though, the original hone marks were still on the cylinder walls after 130,000 miles), added the usual bolt-ons and am finally getting a great blower.
My car has never been to a mechanic.
As far as the interior, well, convertibles are meant to see the sun.
I am looking at getting a set of Corbeau TRS's because they are nicer than recovering the leather front seats anyway.
Lastly, message boards like this really help when you need it.
If you do get one, you'll never regret it.

Also, I think mileage in a 5.0 is totally irrelevant. I'll take one with 200000 well maintained miles over one with 120000 grandma owned/kept in the garage miles.