RE: 04 Evo 92
I don't mind riding my EVOs in B&J conditions, but they are not really made for it. They are high rockered boards and are not so natural in a straighline. This applies to a high degree to the 04 92 (later models being a bit less rockered). Many people do use EVO as high wind boards though (you gave examples yourself), so I wouldn't say they does not _work_ for this. I don't think it will be more problematic for you as a heavyweight as long as you'll be firmly powered up.
A bigger fin will help the EVO in some aspects, but not really transform the general feel.
So, the bottom line is that it will be taking a little bit of a chance when getting an EVO (like you said, a Kombat would have been a safe bet) but since the board also comes at a good price (which IS a part of the equation). Also think about how the second hand market for an EVO 92 looks where you live. If it will be possible to sell the board without a too substantial loss, this would work in favour for buyin one. Another issue that work in favour is that you can get advice from other poeple riding EVOs at your spot, so you're likely to have a good chance of getting the hang on how to sail it effectively.