***Need help***What to look for when buying a 1965 Fastback?

[Montrealstang]

Hello everyone,

I am new to the forum so I will introduce myself. My name is Ben and I am from Montreal, Canada.
While in the States last week, I came accross a 1965 Fastback and I am thinking of buying it. I will tell you guys all the info I was able to gather about the car (not much) and you guys can please tell me what else I need to know (ask the seller or have checked).
From the outside the car looks good, it was originally red but was painted silver. The floor panels and trunk have been replaced with new sheet metal because they were all rusted. The owner said there was no rust left on the car. I think he mentioned he replaced on of the back panels too. The car starts and runs fine. The engine looks fine, does not leak and he said it was original. The only issue with it is when put into Rear the tranny takes a few moments before it clicks into gear. From the inside, the car looks alright, just alright. Carpet needs redone and the dash needs to be replaced.

That is about all the information I have on the vehicle. This would not be a small purchase for me, so I would like to make sure I am not getting ripped off. So what else do i need to know? What numbers should I check? All information will be extremely valuable.
If there was already a thread with this info posted on it, please direct me to it.

Thanks everybody.

B.