Dont think it will make a lick of difference. Wheelies have little to do with power, so long as there is enough of it there (which you got).
I'd practice clutching some more, and switch to first gear. the trick is to lift the front wheel pretty damn close to balance point on the first "lunge", with the clutch. The higher you get the front wheel, the easier it is to hold it, or get it higher (or to loop it). Your 600 will get the job done, and a 1000 will as well. The only consideration against buying a 1000 is the added expance should you mess up. better to practice on a cheaper bike.