How level is 'good enough' for a 8x14' shed's gravel foundation?
I've built and owned several sheds on similar bases. What you'll find is that the weight of the shed and the vibration of use tends to settle the foundation (floor framing) into the soil a bit, eliminating slight wiggles in the surface.
The key is that you have a good average, and that it's level in both directions. Obviously most of the weight rests on the perimeter, so you want to focus on that. Make sure there aren't any areas that seem weak, like they'll slough out when the shed is set.
Once it's set and has a chance to settle a bit, but before you load it up with human junk, check the floor in both directions. If it's out more than say 1/2&quot; total in either direction (my standard; yours may differ), consider levering it up and making adjustments. That's not as difficult as it may sound if you use adequate levers and suitable fulcrums. Either rake a bit of soil out from under the high side, or fling a bit more under the low side.