My dad owns a 1967 2 door mustang fastback that he is passing down to me. The car has set for a while, been kept inside though, and it needs a new paint job along with some interior or sorts. I do believe it also needs a front bumper. The thing that concerns me about the car is that it does not have the original 390 in it. When he bought the car along time ago it didnt have seats, bumpers, engine, and had rust spots on the outside. So he put a 390 in the car but it came out of a station wagon. I wanted to know what I would have to do to build the engine back up to factory specs?

 

To get the engine up to snuff; if you mean driving like the original, not too much. If you mean "as original" it could mean quite a bit of money and work.

I suggest getting on the FE (390, 429, 427) forum and getting some help from these guys. In general, if you rebuild the engine thoughtfully, you'd have a hard time not having at least as much horsepower as the original Mustang 390.

As an example. The original exhaust manifolds did not work that well. The original heads were pretty much the same as all the other 390 passenger car heads. The original "s" intake was surprisingly good. The cam may have been a little better than a passenger car, and the carb was a 750cfm carb. The valvetrain was also pretty mild. So, there was nothing too fancy about the Mustang 390 that you could not duplicate or improve on. One thing to keep in mind though is it is usually more expensive to rebuild and improve a 390 that a 289. I suspect you would also have to change out the pistons to get the compression up, but I'm not sure.

Sounds like a fun car.