The grade has been established by using a piece of 1x2's, screwed into the studs of the basement (metal studs). A section of track has already been mounted and the connecting piece of 1/2" ply has tied together the Cumbres yard limit and the climb to Villa Grove.
On a side note, a friend gave me a good idea when trying to find the metal studs. Rare earth magnets! Just slide the magnet along the wall and see where it bites. Make a mark on the wall and mount away!