TST Products originated the modified fuel pate - theres also more info here:
This is now considered to be just a guide. There lots of people grinding their own custom plates and getting them from other sources.
Bumping the timing will give you a very marginal bump in hp - but, more importantly it will make the truck run better. You should be somewhere between 15-17 degrees.
For some extra performance you should look into a 3k or 4k Governor Spring Kit.
Also, have a look at this: