I was able to drill out 90% of the spot welds holding the (driver's) radius arm bracket (with strengthener!) to the heelboard. I missed one or two, but was too hot and tired to complete it last night. Maybe tonight's the night!?
I also received the driver's side A-Post from Rimmer Bros. It's much bigger than I thought and slides under and beneath much more of the rest of the structure in the footwell than I thought. I might just trim it back to be a patch instead of a complete replacement. Ironically I might have to remove the sill to see if I need to replace the whole A-post. Bleah.