I will be lifting the machine on blocks just for a few hours to clean and repair something, then get it leveled out. Where exactly are those points? I have looked through a copy of a 1950's EE manual and I do not see any information at all on leveling the machine.
Get you a strong LED flashlight, and perhaps a mirror.
There are cast-in holes, one at each of the three points, cored to 5/8" nominal, and tapered to the usual draft angle. as castings are.
From the underside, each exits central to a larger flat, cast 'pad'. You should be able to locate these at HS end just from the departure from line of the lower edge of the casting.
One opens in the clear, behind the DC Panel, a swing-out on an MG-era 10EE.
The other, same era of 10EE, comes up under the motor mounting plate. I moved that one about an inch or so to allow for bolts projecting upward.
The one at TS end, in the opening, hatch over OFF, looks off-centre, but is correctly placed for the balance of mass and stresses.
I opened all on mine up to a straighter 3/4", used long bolts, head-down, to attach skates, permanently.
A few turns of a few hex nuts, the weight can go onto the skates for movement, ELSE bear onto a steel plate between the 2 axles OF the skate for fixed operating.
"Leveling" to any precision not needed unless preparing to assess for need-of, or actually DO scraping & c.