Which should I install first?

[Dejavu]

I have the drivers side cowl removed and cut out the remnants of the vent on my 66. I want to install the toeboard before I replace the cowl because I have great access to the top through this gapping hole created by the vent removal. My question is should I replace the floor (did I forget to mention my project is called RUSTBUCKET) before the toe board?
Thanks,
Fred