Changing from 540 to 1000 pto

Whatever brand/model #  of cutter you have, call an Implement dealer that actually sells/services them and they can tell you. I imagine SOME can do this, while many cannot. You'll still have to adapt to the large 1 3/4" shaft on the tractor regardless.

Like Dr said, it's going to depend on the manufacturer and the model.  Some had gear boxes you could easily change out parts to go from 540 to 1000.  The woods B320 is one example that was a little more complicated, as the difference was both the front section of the gear box and the input shaft (it was a smaller gear, so the front cover for the 1000 rpm batwings set the gear lower down than the 540 models if I remember correctly).  Also, if I were you, I would buy the yoke with the 1-3/4" 20 spine 1000 rpm section and change that out on driveshaft instead of using an adaptor.  If you have a driveline with an equal angle drive, you will mess up the geometry with one of those adaptors.  With a CV driveline, you could probably get away with it, as the driveline geometry is not as crucial (assuming the shaft is no where near bottoming out).  That being said, the yoke probably won't be much more expensive than a GOOD adaptor that can handle the power.  Hope this helps a little.