[MagicRat]

Those Mustang II's were quite wothwhile. In the late 70's, most every domestic car being sold was pretty crappy for looks/performance, except for mustangs, camaros, f-birds and corvettes.

Lots of '70's cars are now collectalbe, including yours. Yours is especially worthwhile because its pretty much a one owner car after 27 years, and was a top of the line model.

I would suggest keep it fairly close to stock, restore it, dont customize it, to preserve its collector value.
If you have a 302 V8, there are lots of easy bolt-on mods to boost power, such as intake manifolds, carbs, headers etc. Since all these parts are bolt-on, you can reinstall the original parts if you wanted to sell.