This is definitely a "try before you buy" situation.
I am 5'8'' and about 275 and fit just fine sideways. You might be too tall and I seriously doubt size 15 extra wides will work in the foot well.
I don't know, however, I am just guessing. I would not buy from someone who won't let me drive it or even sit in it.
Go do it! I'm afraid you will love it...
*s*
