I'm interested in doing the same thing with my '02 4.3 V6, so I did a little searching. Here's the best alternatives I could come up with...
1. Get a power programmer or a chip and it will get rid of the governor.
2. You should just be able to unplug the speedometer sensor cable, and tie it back out of the way. You will have no idea how fast you are going, but the computer shouldn't either.
3. Superchip has a product that plugs into your OBDII slot and can tweak settings, then you unplug it and throw it in the glove box. If you ever need to go to the dealer for work or anything, just plug it back in & reset factory defaults
4. Do you have a manual trans? if you do, you can just unplug the sender for the speedo. This doesn't work on automatic vehicles though, since those wires control the shifting.... Anyways, it is much easier if you have a V6 to just raise the governor, don't put it at 128mph though, the driveshaft won't handle it but a few times.
NB: Basically, when you raise the govenor on your truck, you are changing top speed from 98mph to like 120ish. Another thing the stock govener does is cut the fuel off once you hit the top speed.