These original cadenzas for Mozart Concertos are freely available for download to anyone who'd like to use them.
My philosophy is, it's a cadenza, so if there's something you don't like or doesn't sit well in your hand, change it! (That's assuming you're able to do so in a stylistic way; I guess Edit at Your Own Risk would be the appropriate caveat.)
You will note these are attempts to write cadenzas more or less in Mozart's own style - of which we fortunately have a number of examples - with a few early-Beethovenian type licenses. For insight into this process, the chapter on cadenzas in Paul Badura-Skoda's Performing Mozart at the Keyboard is an excellent guide.
If you check these out I'd love to hear what you think! And if you do use one in performance, assuming you don't alter it beyond recognition you might be so kind as to attribute it as appropriate - many thanks!
- J.W.
Cadenza, Mozart Concerto K. 467, 1st mvt.
Cadenza, Mozart Concerto K. 467, 3rd mvt. (this is a funny one)
Cadenza, Mozart Concerto K. 491, 1st mvt. (this one... not so funny. Writing cadenzas for the minor key concertos is a big problem, as we have no Mozart models and the expressive context is so very different from all the others. It's a challenge to make one sufficiently dramatic without being too long and overblown. This one may yet err on the latter side, but it's a shot anyway.)