Don't know if the mustang pan (should be a dual sump) will fit, you may have to dig up an original style front sump pan.

If the 64 was not a stick car, you'll need to dig up a peddle assembly. The 64 would use a mechanical clutch linkage and the Mustang unit uses a cable or hydraulic set up so some fabrication will be needed in this area. A driveshaft will also likely have to be built.

If your going to be using the original induction from the Mustang, you'll have to figure out the computer wiring and figure out how to install a fuel pump capable of supporting it. If your planning on changing to a carb, I believe that you'll have to install an electric fuel pump as your 302 dosn't have the provisions for a mechanical pump (this was discussed in a previuos post so you ight check the arcives).

Although I tend to agree with madgringer and would go with a bigger engine (I'm just an old hotrodder at heart, and I hate to see a lot of wasted space in an engine compartment), a lot of these were produced with 289s and made good cruisers. With the 5 spd and the weight of the car, I'd see what gears the rear has, and set it up with about a 3.55 set.