An older Bayliner with kow problems only spells many more problems.
Your water leak may just be a open water drain plug. Can you inspect it
in the dark with a bright spotlight so you can find the leak? The shift
cable can only be replaced by removing the outdrive(replace the
impeller while you are at it). I would take a serious look at the
stringers and transom for rotting before I bought it. Any signs of
water intrusion and I would pass on this boat. Been there done that.
Good luck.

Mark