Before looking for pistons, I suggest doing some measuring. The results will determine what size piston you need.
1) Be sure to mic your old wristpin, 302s used two different pin sizes .990 on earlier 302s, 1.050 on the later ones. Larger rods can be bushed down to the small size but not vice versa.
2)Also it would be wise to check wear and taper in the cylinder bores to be sure that the block won't need an overbore. I'd be surprised if there were no scoring damage from the pin keeper failure.
GMC 302 pistons can be hard to find and expensive. The rings are an old wide style and often cost more than the piston itself, if you can find them. Good Luck
