Shortened the left engine mount links another 3/16" each so I could get the mount short enough to level the engine on the roll axis by sighting the two mounting lugs with a cross tube from the rear of the frame. This brought the oil tank too close to the frame and also put the pulleys out of alignment slightly so I had to re adjust the front drag link to push the front of the engine to the left about 1/4".
The engine pulley now measures within .1 degree of the trans pulley for level and has less than 1/16" twist (forward on the left, back on the right) measured at the edges of the pulleys with a straight edge. This minor belt twist will be reduced further as the transmission torques under load.
Replaced the hardware store nuts on the mounts with the AN locking nuts and torqued according to the instructions and verified that the tops of the mounts remained level.
Figured out a way to check the idler pulley with the digital level and determined that it's within .1 - .2 degrees of level with the trans and engine pulley. It does appear to be very slightly out of alignment on the vertical plane but not sure it's enough to warrant filing the hole, will re-watch that section of the build video to see if a tolerance is given.