In need of help
 

I just got this mercury and it says Monterey and s55 , I've tried to find images of the car that way I can start gathering parts but none has the roof line or taillights, also I would like to know how to find out what engine I have , I was told 390 or406 , any help with letting me know about this car is greatly appreciated,I fell in love with it and got it lol
https://cimg4.ibsrv.net/gimg/www.mer...208022e2ff.jpg
https://cimg6.ibsrv.net/gimg/www.mer...94a1606551.jpg
https://cimg7.ibsrv.net/gimg/www.mer...e5df2ba8e2.jpg
https://cimg8.ibsrv.net/gimg/www.mer...d63840c489.jpg