Not trying to upset the apple cart too much here, but does PayPal need this level of proof? Or would they accept a note written up from a local mechanic on his estimate form. Let's say he provides you with something stating installed customer supplied injectors and then reinstalled customer's stock injectors because replacements were defective. Or that he bench tested injectors and found no fuel flow etc. I'd hate to see you could be throwing good money after bad here. What about pulling the tips and just cleaning them and swapping them onto your bodies?
Those would be some expensive tips..