RE: What wave board?
For Eastern Lake Ontario in 15 to 25 knots and sails up to 6.3 I would go with a Kombat 87 or the Fanatic Freewave 88. For the light winds you are talking about the big waves are not really happening yet. You want a board that really gets up and goes. Something that is fast and good for jumping. Too early to be getting a full on wave board for a guy your size. Besides you can switch down to something like an Evo 75 for sails from 5.4 and down.
I used an Acid 94 for sailing Lake Ontario for a few years. It was one of the most versatile boards I have ever owned. I think the Kombat is a good replacement for that board.