For the best accuracy of any machine tool that has ways, like lathes and mills, they must be leveled. You can't expect accuracy from ways that have a twist; it is not the absolute levelness that counts, but the consistency all-over. A lathe could be mounted vertically on a wall and as long as the ways were not twisted you could expect the accuracy that the maker built-in. Leveling will not make a poor lathe better but will at least enable you to get the maximum the lathe's builder designed and machined into it. A lathe with prismatic ways will require a pair of precision spacers to get the level riding above the prism, measuring across the flats of the front and rear ways. It isn't critical that they be precision blocks, since as I say above the absolute levelness is not as important as the consistency between leveling points. I used a pair of Starrett precision ground vee-blocks on their sides but the important thing is that you put whatever spacers you use in the same relative sideup/sidedown and front block/rear block for each of the two measurements cross bed.

For this HF8x12 lathe, I chose to use the bench legs as my leveling adjustment rather than shim the lathe legs. I did this because this lathe has its mounting bolts inline in the longitudinal direction rather than at the four corners (two each leg) as in most smaller American built lathes. While this inline fastening might appear to make shimming easier I feel that it will only work if the bolts are torqued accurately with a precision torque wrench after each adjustment attempt. In addition the deflection of the bottom of the leg (a box shape) in the span between shims can aggravate the shimming exercise to the point of failure. Tightening and loosening the three bolts with a torque wrench between each adjustment is also more than I have patience for. I started out with a rigid metal faced benchtop, reinforced with a strongback underneath, and felt the lathe would be happiest firmly and squarely mounted to that surface first.

If you will be using a "soft wood" bench top for your lathe it is quite possible that a lathe of this weight, with this leg area, can deform the surface of the benchtop, especially at the headstock end. This will make leveling more difficult. The addition of two pieces of steel plate, say 1/16' or 1/8" thick, under the two legs and about twice the area of each leg should greatly help the process.