Hi Chas (Charles? Chuck?)

Welcome to Chevy Chatter.
First of all, I'll give you a general reply. 1939 is a fairly common, and available, year. My gut says that you should be able to find all of the body parts if you look around enough. Did you search through our CLASSIFIED ADS section? Back on the homepage (
https://vccachat.org) it's about half way down the page.
Secondly, our club, and this forum, tend to primarily support original and restored vehicles and trucks... We don't discourage modifying the cars as you appear to be doing, but you may not find too much support here since that's not a big objective of ours.
The term "Speedsters" is one that was formally used to recognize those cars that were modified in the 20's and 30's in order to make them more "sporty". And... in some cases to convert them into actual RACE CARS. I don't know what the year cutoff is, but I think it would be the early 30's. (Maybe someone else can jump in here and clarify for us.)
It's great that you're resurrecting an old Chevy and you may find parts here that you can acquire (verses eBay), or you may want to offer us any parts that you end up not using. In total, it ends up a Win-Win for all of us.
Good luck.