Stepside bed angle welding-placement

[forcd02]

My 70 stepside had some ugly floor installed, so I rem. it, but the factory angle brackets were rem., and I need to weld new ones on.
It looks like I need the board with the milled side to get the right depth so the
board will slide under the angle bracket.
I looked at the Mar K pick, looks liked they used a small section of wood for the spacer-anyone done this, and what did you use for a spacer-I don't have the wood kit yet.
Thanks