Sorry to hear of your troubles Steve and i hope they get it all fixed up.
I dodged a bullet myself seems i had a voltage regulator catch on fire and dont know when, pulled the cowling off to look things over and some black crap had leaked down the back of the engine block took it apart and found this. Seems older mercury's are noted for this...cost for OEM regulators about 400 bucks,, the new ones have a fuse in them.