the impeller is due, the PO did it just before i bought itnah, not really, all you will do is foul the plugs faster and have a little more smoke, AKA james bond, lol
check the LU grease, just to be safe ................
when was the water pump last done ???
If you want to satisfy your curiosity about the lower unit, just have a vacuum/pressure test done it. It's pretty simple and a tech can do that under an hour easily.