Made F-684 gussets (these stiffen the longerons to the firewall - had to do some cuts, layout drill holes, and put a couple small bends in them to conform to the attach angles). This is a little tricky in that you want to test fit and ensure edge distance clearance for your drill holes on both sides of the gusset. Some builders screwed this step up - I purposely didn't trim off as much of the tip as Van's recommended, and modified the cutout notch a little to ensure good edge distance before drilling holes and that the gusset sat 1/8" back from the firewall. Then I drilled. Went well.
Before and after trimming/drilling
Had to peel skin back and use right angle drill for this row