Where are you located in IN?
when the old motor is out just swap your mounts and what ever else to the regal engine.
nice low miles engine you found there.
well being you should be doing a lim job on the regal engine before it goes in. its easier that way, you can do some test fits, if need be buy new metal elbows and use your alt bracket and alt, as it maybe different.
the blocks are the same, any thing you want or need to swap over will just swap over.