I bought a 1983 mark twain for $750 is that too much?

The boat is in good condition it is one of those square faced ones not with a tip on the front and the boods interior and exterior are good needs minor fixing and a new engine and needs to be fully restored but as for an engineand steering and speedometer should i give it back because when ibought it they said it is a1990 mark twain and now i found out it is 1983 so can i return it or should i or should i keep it and try to fix it?