First time buyer/restoration advice

I have always wanted a Ford mustang from either 66 or 68. I now have the opportunity to buy one! It's a C code V8 coupe from 1966. For the most part, it's rust-free with one or two (badly patched) rusty areas. At some point in the 70s, the owner swapped out the V8 for an inline 6. In 2021 the owner decided to restore the car and swap back a V8 but only got as far as to take out the Inline 6. I have an appointment to check it out on Tuesday. The price is approx half of what running coupes go for here. He has a few V8 engines that he is willing to sell for anywhere from 500$ to 3000$.
A few more things about the car: Steering wheel, wheels, and front seats are ugly-looking aftermarket parts. In the pictures, it looked like there were one or two dents. The headlight buckets are either not fully screwed in or the fitment is just terrible because there are huge panel gaps. The car used to be burgundy red but was repainted with candy apple a while back. The paint job looks ok. Breaks, transmission (automatic), electronics, and suspension all are in good shape and have original V8 parts according to the seller. The Interior is in a state where I would be ok with not touching it but obviously not showroom quality.
My questions:

1. Am I in over my head swapping the V8 back in? I have some experience working with older fords (Ford Taunus 1965) but am not a mechanic. I have access to most tools, friends willing to help as well as a car lift.
2. Is there anything mustang specific I should pay attention to when checking it out? (Things that will end up costing me a lot of money/time to fix etc)
3. Any other advice is also appreciated!

EDIT: A little bit of extra info
VIN: 6T07C158163
Asking price: 10990€ (In Germany this is a great price for a mustang. Driving cars go for around 20k)
I am really not trying to restore to showroom quality and am ok with subpar results as long as it drives and looks good from 6ft away!
It comes with papers.

A small update:
The seller never answered my questions because "i don't have time to answer so many questions".
I then asked him if there was any wiggle room on the price or not (I had no intention of paying 10990 but never got as far as to tell him). He decided to insult me because "i never discuss prices over the phone, you don't call the bakery and ask to negotiate the price of bread". Then he said he finally looked at my questions in the email and who I think I am to ask them and what am I expecting from his car. Following that conversation I of course informed him I won't be coming to check out the car.

All in all I am so happy I came here first and thank you all for your help. I really dodged a bullet imo.
I guess he was hoping he could sell the car to some unknowing idiot (me) and get away with it.
You guys just saved me a 7h drive, a lot of money and time, thanks!

In case you were wondering what kind of outrageous questions were in my email here are just a few of them:
Was the car in an accident
What happened to the I6
Why are the body panels so lose
What's that weird patch in the trunk
Are the original motor mounts included
What V8s he has on hand.