Update: Looks like I'll be buying the Trek 820 everyone! It fits me well, and the buyer was willing to sell for $90 so I'll be picking it up tomorrow

I did have a few questions though. Is there a particular set of wheels I should look at putting on here? Also, specifically what modifications should I make to accommodate for my size? I plan on taking it to my LBS, but I'd wanted to have an idea of what should be done to the bike to accommodate for my size before I took it to them.