Some basic questions re 727 and 318/360 bolt up

New to Mopar, so forgive me if some of this is dumb. I have a '67 a100 pick up that had an early swap to a slant 225 and has the original 3 on the tree manual 727.

I have too many other projects to make this a big one and just want to get it running and will tinker down the road.

The 225 is pooched, would need a top and bottome end build. My local yard has a 1977 camper van with 177KM and a 360 plus a couple of what look like 1992 318 magnums (unknown KMs). I am leaning toward the 360 because it has known mileage.

I understand that these motors will bolt up to the existing 727, but are there any other considerations? emissions on the 318s? spline counts the same? motor mounts the same? other considerations?

Thanks