Every wedgehead has its own best pitch setting, there is no one "correct" setting. Some tables are better when they play faster, and some are better when they play a little slower. As already noted, it's important that the game be in good mechanical condition and playable (decent flippers, no sunken inserts, etc), but pitch is important, too.
I use two-inch levelers in the front with thin jam nuts below the leg, and three-inch levelers in the back with standard thickness nuts positioned below the leg. I run the front levelers in as far in as possible, adjust for left-to-right level as needed, and then lock the leveler position with the jam nuts. I run the back levelers out a bit more than half way, level the game left-to-right, and then lock the leveler position with the standard nuts. Note that the back locking nuts are important as they help to support the weight of the cabinet and head. If you don't lock these nuts up against the underside of the leg, they don't provide any support, and that tends to put extra stress on the threaded holes going through the back legs.
After setting up a trial pitch, I play a few games. If the machine seems slow I'll raise the back levelers more. If the ball is dropping too fast to the bottom, I'll lower them. It isn't really that difficult to get a feel for the best pitch of any wedgehead, just experiment until it seems right.