good swap for pre 85

The engine in my 83 sundowner is starting to use a lot of oil and its time to replace it or do a swap so Im looking for some good ideas. This is my daily and my show truck so it needs to be reliable and cool looking, anybody got any good suggestions

O yea the trans has lost 5th gear so its got to go anyways

Find you a diesel from the same year mazdas.

I didnt know they made them in those year models