Sounds like you want a reliable driver for you and the young lad? Nothing too hp crazy? Post(like you did) what your goals and your skills are. Members here will be able to help guide you BUT if your skills are limited you could get frustrated. It's hard to interpret/translate everything thru the net.
You could have someone(a member) in the area drop by for an afternoon to help assess/diagnose the problem(s)? Offer up a meal and a beer, and make a friend? Then from that point you could assess whether an engine swap us what you want. Black smoke could also be valve seals?
Just trying to offer up options.
Good luck
