The engine that is currently in 5052 has been running with a welded motor mount ear since 2002 (the ear snapped off while trying to remove a seized / broken motor mount stud). I ended up taking the entire engine to a welding shop which was experienced in aluminum repairs. From what I recall, the repair cost was $80.

As long as the welder is knowledgeable in the art and skill of working with aluminum, they shouldn't have too much difficulty making a lasting repair.