Finally today, I routed the "L" shapes at the back of my main sills
I just followed the guidance in The Cabrioletter (#114). The article suggested cutting 'about' 1/16" deep, but I cut a little less. The bases of the two pieces that fit on top of the "L" recess are only 0.035" thick, so I went about 0.040-0.45."
I have been fitting new wood for the doors, too.
Some of the wood pieces had to be completely re-cut, and others additional thickness had to be added, but most only required a little shaving and the normally expected fitting effort.
This is the two rear door wood pieces and the photo shows the right door lock hole and with the set screw holder in position, threaded through the two pieces.
The piece that fits at the top of the door needed extra work.
The reproduction piece was nearly 3/16" too thin at its top edge. The unpainted strip was thinned down to proper thickness and glued onto the reproduction piece. The resulting piece looks a bit oddball, but has all needed mating surfaces and will not be seen after door is assembled.
As the sheet metal on these Briggs Body doors was originally skinned on top of a wood and metal frame, replacement of just the wood can not be done in the same manner as the door was originally constructed. This top piece is the most difficult to place back into the metal framework. The Cabrioletter suggested using a two piece top piece; but with a little modification, I think it can be installed as a single piece and be stronger than a two piece one would be.
I will await final assembly of the door wood until after the door skins have been sand blasted and primed. The sheet metal is amazingly good on these doors. The only patch needed was from a tear/crumpling coming back from the door handle, only about one square inch of metal!