No good. If you have tapered head set you need tapered steerer. 650 forks are available and probably not cheap 27.5" should work. What is wrong with your current ones as they look nice? Also as I mentioned on another thread you need to consider your axle type as those ones look like a 15 or 20mm maxle no good if you have std 9mm QR type.
You will need a headset reducer, Chris king or hope would be my choice.
It's a nice idea but will effect the handling quite a lot. You'll also have 2 inch more travel at the front than the rear.
DVO make some nice upside down forks with a tapered steerer but very expensive.
You also need to see if Crank Bros make a 20mm through axle conversion kit for the hubs. You will also need the 27.5" version forks if you're going with Fox 40's which are the most recent model.