I didn't actually measure the backlash so I have no value to give you for reference. Joe didn't provide an expected value either. After assembly, I did roll the motor over a few times slowly by hand to be sure there was no binding due to minute variations one would expect but discovered nothing but a smooth consistent movement.
I did the assembly with a very light coat of STP on the gear teeth applied with a horse hair brush just to give me a warm fuzzy feeling that there would be adequate lubrication until the first start.
The hardest part of the whole process was fitting the oil pump gear with it's devilish little ass key.