Is it a convertible? If not then things make very little sense. If it is a convertible then maybe someone swapped a v8 into the car at some point. I'm not sure if it will have it but see if there is a vin stamped on the engine block.
Also, I would check with the seller... I would probably see if he would take it back since you have no idea what (or who's for that matter) car you have. You could run into some issues down the line both with the title and you never know, it could be stolen or have stolen parts. The seller should know and should have told you if the engine was swapped and told you that it is a 95 not a 96.
If the seller does not want to take it back but knew about these issues you could probably take this to court but that's gonna be your deal if you want to keep the car or not. I personally, would want to get as far away from this as possible.