What truck do I have? For the Chevy Gods, Historians and Know it alls

[Snake Eyes USA]

Hello Classic Chevy Truck Family. I'm new and somewhat happily forced into the classic truck scene.

Ive been racking my brain in trying to figure out what year and model truck I have.
Quick back story. Ive inherited the following truck as to keep it in the Family. Imported the truck back to the U.S. from Canada where it belongs. U.S.A.!
The previous owner claims it is a 1970 GMC C1500 and converted to a 71 Cheyenne. While doing some research I'm finding some things do not add up. Ive attempted Vin. I.D. but get lost at about the 5th or 6th digit.
Here are pics of the truck and vin. card information.
I would love any help I can get. The truck needs very little work and plan to have back on the road very soon.
Feel free to ask questions.

These are the following sites I found to help me out or confuse me more. Depends how you look at it. lol Quite useful for any 67-72 Chevy/GMC Truck owner.

https://www.edmunds.com/gmc/sierra-1500/history/

https://en.wikipedia.org/wiki/Chevrolet_C/K

http://www.trucktrend.com/features/1...pickup-trucks/

http://67-72chevytrucks.com/

http://www.pattson.com/maych/67_72_gmc.htm

http://www.pattson.com/maych/67_72_chevy.htm