long runner

Just need some advice I bought a 1978 dodge that take a Mitsubishi diesel motor. The truck is in mint condition there is no motor. I was thinking to put a Cummins motor in it. I came across 1978 donor truck with a Mitsubishi motor. Not to many of these truck were made and they only go 70 click. I did get the donor truck, but wondering how much money I should put into it and would it be worth it