The Myford ML7 User's Manual, widely available in free PDF form on the net, has about the best run through on setting a small lathe bed level. But trying to get the bench level to the same sort of precision is a waste of time. In fact, many deliberately set the bench off-level so the coolant drains to to one corner for collection. Yet others just sit the lathe on the bench, loosely bolted down at the headstock end only and let it assume its natural position. If the lathe bed is not warped, it will work fine like this. My own ML7 is on a steel bench that is not bolted to the not-flat concrete floor and the lathe itself is packed up on two pieces of 20mm x 40mm soft pine wood with the mounting bolts running through them to the steel bench top below. It turns parallel to within less than two tenths of a thou as near as I can measure. (This was a temporary set up when I was overhauling the lathe but it works so well I left it like that.) So there really is no definitive way to set the whole thing up. As long as it turns parallel at the end of the day, all is good.