6'3" and 215 is not a big deal for any of the cars, provided they're set up right to begin with. My car fits me like a glove and I'm taller than that. But, I've sat in Kirkhams, CSX, and SPF cars where I didn't fit worth a crap because the owners were diminutive in size.
I don't think I've ever sat in an FFR, but I know for a fact they can be set up for taller folks. You don't need an "extended wheelbase" for your size. And don't worry about getting a chance to work on them just because someone else put them together. Even if you have one built by NASA, it will still find a way to fall apart just sitting in your garage.
