Well, your horse's sire is out of Rugged Lark, arguably the most incredible AQHA show horse to have ever lived. He won the AQHA World Show Superhorse title twice over his career (basically means he was the best horse in the world no matter what discipline, bar none -- twice.) He is the reason Lynn Palm is so famous in the Quarter Horse industry. She was his exhibitor / trainer. He is also the only Superhorse to produce another Superhorse (actually he's sired two other superhorses), and some of his off-spring have done some other pretty awesome things in their show careers as well.
His bloodlines are a bit of old news though. He was absolutely huge in the late 80's and early 90's and he performed his farewell show tour in 1997, hitting many of the major shows in the USA. Still, Rugged Lark lines are nothing to sneer at, and probably never will be. He died on Oct. 26, 2004.
Anyway, I don't know much about your horse but his bloodlines are good. I can't seem to find much about the actual sire, but Rugged Lark is an outstanding name to have on his pedigree.
Also, I have to agree with everyone else. The seller has no right to withhold the actual papers. If you want to show, that's your own business. I wouldn't buy him until she agrees to hand over the paperwork.