As long as you have both engines sitting there. There will be subtle difference between the two(valve covers, accessory mounting, thermostat outlet, etc.) but the core long block should be the same. You'll also have to swap the SAE flywheel housing out for its dodge counterpart and reuse whatever flywheel/flexplate you have on the old motor. You'll also have to swap motor mounts and the computer(or have the bus one flashed to work with the dodge pcm).
Like I said, if you have both engines out and beside each other. All you essentially have to do is swap the parts off the dodge engine that don't look identical to the ones on the bus engine.