brake switch on the 64 mustang

If your 64.5 had the brake light switch on the master cylinder, you will need the pedal mounted switch like 65-66 has.

Put a "T" fitting between either of the brake lines coming out of master cyl and the master cylinder itself. Attach the brake line you removed to install the T to one outlet of the T, and attach your old brake light pressure switch to the other outlet of the T. Re-attach the original wires back to the pressure switch and your brake lights will work again. Simplest way. No rewire. No adding brake light switch to the pedal and re routing the original wires to it. If you are careful and not shake the fluid out of the brake line after you remove it, all you may have to do to bleed it after it is assembled is loosen the brake line while someone pushes on the brake pedal to bleed the air out of the fitting. Check the pedal. If it's solid you are done. If it is spongy, you will have to do a normal bleed on one of the wheels the brake line goes to.

That sounds like a good idea as well.