My key issue was getting the 3 angle supports at the right height and coplanar with each other and the top of the stub wall (it was -- thanks to carefull use of a 4' level when installing the vertical members!). Less than 1/16" error which was taken up with a bed of clear silicone caulk on top of the stub wall and each angle bracket.
Walker Turner 12" Bandsaw and Powermatic 65 Table Saw