The very top of the fill valve (the one with the black cap on it that has the float) should be just barely under the top of the open tank. Place a ruler across the top of the tank to verify. Once you have it properly set, measure from the bottom of the tank to the critical line on the fill valve. The top of the flush valve (the one with the black plastic tube open at the top with the flapper on it) should be 1 inch below this line. Once you have the water level properly set, the water level of the full tank should be 1/2 an inch below the top of the flush valve. Use a small pipe cutter if you need to shorten it.
Using the example of the three tank bolts being at 12, 4, and 8 o'clock, you should install the flush valve between 12 and 4 instead of 8 and 12. Also shorten the rubber fill tube to where it has about an inch of play in it.
Lastly, be sure to set the roller on the blue adjuster to where the bowl stops filling up and is full right when the tank stops filling. Somewhere between settings 6 to 8 should be it. This will save you several hundred gallons of water and money over the course of a year.
Here is a picture of one I just finished: