I will let the gurus deal with the engine pad and geography issues.
The sales invoice and order form are standard Reynolds & Reynolds documents used back then. The sales order would have been filled out by the salesperson and signed by the customer. You will note the salesperson's name appears at the top left and his signature is at the lower right.
The SA-131 invoice was a stock from which was crash printed and numbered by Reynolds for the dealer. You will note the dealer imprint and numbering are the same color...my recollection is the crash printing was done in black, but it has been a long time since I dealt with these forms??
Window sticker seems too clean and neat to be an original 50 plus year old document.
All that said, a Hugger Orange LT-1 Z28 with a 4.10 gear would be fun to own
-wilma