I bought what sounds like the same vinyl repair kit Kevin mentioned in the early 1980s and it worked very well for me. The material lasts a long time, also. Mixing for color is important...really important. In your case a lighter or darker color might not show too much due to the size of the spot. I don't remember backing material in my kit but the vinyl stuff bonded and lasted for about 3 years (before I sold the car). I used it to repair a tear in the seat of a Datsun 510.

~ Jon
1952 1/2 ton with 1959 235 | T5 with 3.07 rear end