65 Barracuda w/500ci RB, Stage VI Max Wedge Port Heads, 6-speed, and 5.38 Dana

Hmmm,spare tire. Well I suppose a space saver could be mounted underneath. If all your worried about is getting home and not paying for a tow,it could go where the original gas tank mounted.It will definitely look weird,one fat tire and one real skinny.
Nope, absolutely no way it could go where the original gas tank was. Besides the cell being longer than an original tank, you will see earlier in my buid that I relocated the rear axle further back to allow for a taller rear tire without modifying the body.

I can get my wife or a friend to give me a ride home, grab my truck and trailer to get it home if the situation ever arises.