Check out my 73SS restoration at www.cardomain.com/ride/2276164 (http://www.cardomain.com/ride/2276164)
I've been working on it for a little over a year now.

Nice work on your car, What color will you be painting it? Was it a factory 4 speed?

I don't understand why you would want to put spray on bed liner on the underside of the car. If it is properly primed and painted the metal will be protected. If you decide later you do not want the bed liner material it will be worse than the undercoating to remove.