Finally get to pretend I am one of the cool kids - Holley kit swap
I like the idea of using the tunnel from a late model, but it proposes some problems. Carpet being the obvious, second would be the stock A body console would look odd on such a wide tunnel. I also wonder how seats will fit. Mine pretty much touch the console and this looks much wider than stock where the seats will go. Lastly, it appears he removed the inboard seat belt mounts with the installation of that tunnel. Not a big deal as they can be added to the new tunnel. I'm curious as to how this project is going.I understand. I like the idea that I don't have to weld a seam all along the floor, but in the end a one piece tunnel welded all the way around probably is less welding in the end. Time will tell.
I don't think the 8HP tunnel is anywhere close to the size of one that fits a T56 in my case either. The T56 seems to be much taller just looking at how far up into the firewall my cuts are compared to yours.
If I were to do a one piece tunnel, I would consider a tunnel out of a late model Mopar like @Cool Hand did here.
But I wouldn't want it to go so far back. And it would be buckets only.
And no idea where I would even source the tunnel.