So I made a few changes to the prototype in the shop. Not to much but I did lower the parallel arm 3/4". about as low as I can get it. The further apart the arms are the more they stay in parallel. To mount the arm to the trunnion I decided to go with 2 1/4" blocks. I can mount one to the saw to give left right adjustment. and the other mounted at 90 will have up/down/front/back alignment. So I can tune in the position of the pivot. I also increased the size of the ring 1/4. and shortened the overall length of the arm.