I'm posting this because I wanted to be the FIRST person to ever post on this Forum topic!
I do own a 1990 Sportsman, with a Volvo 290A outdrive and the 350 chevy (570 Penta).
I have some GOOD knowledge of this setup, although not an expert. I have dis-assembled most of my boat to fix even the most tedious things....so I might be able anyone who needs it.
I would love to chat with anyone who owns or owned this model boat about a few minor quirks, and how it handles in different seas.