I am going to be getting the full floor pan. Left right and trans tunnel.
Should I get the one with the braces or not?

I put rear pans in mine and the braces were still in good shape but I cleaned all surface rust off and shot them with primer. It really depends on how bad a shape yours are in once you get the floor off.
Others will chime in with more advice so stay tuned.
Also welcome to the club, and I too have a 70 with a Big Block.
Corpus is a great place we go there every summer, we may run into each other next year.

Which braces are they exactly so I can check em out?

Corpus is alright. If you ever see a atomic orange with a black stripe c4 corvette thats me. It stands out well.

I hope to have my elky drivable by mid to late summer.