That year model has more room in the engine compartment than my 1st gen does. It should fit with little problems on that note.
Now the bad news. That year uses a straight axle. This makes it easyer to install a Cummins. But the front axle and springs are way to light for the engine weight. The brakes were drums. So you would need a full update on the brakes also.
The rear axle is to light also. The biggest they installed was a Dana 60. If you run a auto it would hold for a while. If you run a stick and think of playing, carry a spare axle to get home on.
As far as year of engine. Any would fit. You will need to make mounts anyway. They narrowed the frames on Dodges in 72 model year change.