Help me determine value on 72 C10

[tll74]

I'm looking at buying a one owner garage kept 72 C10 Cheyenne, 350, AT, Tach, Tilt, AC, Long box, Cargo light, Dealer add second tank, Smooth rear bumper, full hub caps, and Front bumper gaurds. Blue and white. Never wrecked and still original paint. Miles are 100k. Although it looks like a very easy 20k. Picture going to Grandpa's house and seeing this truck in the garage. This truck is absolutly mint inside and out. The inside of the box is like new other than a few scratches in the floor. No canopy holes, speaker holes, antenna holes, and etc. This is a true survivor. No price given, I need to make an offer but need some input from you guys to help determine a fair price for both sides. Thanks