Anyone know anybody that has built one using the Brock plans? I am stumped with one area. He calls for 90 degree holes pre-drilled in the seat at pre-determined spacing and also 90 degree holes, with slightly wider spacing in the bottom of the head rest. With the spacing different, I do not see how the spindle can possibly fit in 90 degree holes. The spindle has a curve back to the spindles, so that possibly could get it close, but 90 degrees..... cannot see it.