The cowl looks local RHD which would have had a wood sill somewhat like this:
https://i.ebayimg.com/00/s/MTIwMFgxN...Y~xrP/$_20.JPG
The old sills in the photo look like tube for wood replacement, hot rod style.
The quarter panels behind the doors would be repo? They don't look like local panels.
If repo they should match the steel new sill.
The cowl "should" work with the new steel sill.
Thanks for the photos Brent!
http://www.model-a-ford.com/proj_12.shtml#