Floors pan and trans tunnel suggestions

I'm about to re-start my Dart Sport project and I need some help/suggestions.

I've got some floor pan damage that I need to address, but I also want to address the trans tunnel. I want the tunnel to be capable of accepting a modern trans (Nag1 or 8spd) if i decide on a G3 Hemi swap. I found a company that has a pre-fabbed trans tunnel setup (USCT Motorsports), which I like the idea of.

So in an effort to plan this out; what's the best way to approach and get this all done? I've attached a few photos. Thanks in advance!