With the upper and lower angles cleco'd in place, it's time to move onto the tailwheel mount. Positioned it in place after drilling the angle using the vertical channel as a guide, but the 3/16" spacer pushed it out far enough that the angle of the mount tube was rubbing on the lower mount angle. Removed the angle and chamferred some clearance; took several fits / retries to get it right. With that done, Moved to the rearmost bulkhead.
Positioning this was quite easy - it butts right up against the inner brace of the tailwheel mount. Positioned into place, clamped, and drilled. Of the 10 holes thru the angle and bulkhead, 4 will be up-drilled to accept AN3 hardware, and 6 spots will have rivets. Up-drilled the AN3 holes only to 1/8" so far.
Spent some time disassembling it all in order to move stuff around enough to allow the shear web to fit into place. Once reassembled, did some rough positioning of the web to make sure it can fit accurately in the specified 4.125" from aft edge distance. All is fine.