Thanks again Les. U are still able to do trigonometry! (I have my slide rule somewhere here. I could do that calculation and actually understood the binomial theorem for a microsecond back there in some undergrad class....)
I believe that the levels in the vertical plane are within that 35mm. Will align the faces to as close to parallel as possible with my existing tools (a builders level, but a good one!). The horizontal plane is more tricky and I may use the steel rods described above. Here's hoping!
Merv