Finally get to pretend I am one of the cool kids - Holley kit swap
I fabbed one myself. It's pretty straightforward. I made up some cardboard templates with everything in the car and the tunnel cut out, then welded them up. Front and back were maybe 1/8" flat plate with a 2" or so wide strip between them to make something like a C channel/I beam. I used the original outside bolt of the stock transmission crossmember and drilled a new one outside that to have two per side like stock. The main lesson I learned was to make sure you double check everything is where you want it before making the templates. When I made the first one I must have left the transmission jacked up overnight and it sagged and was way lower by the time I got to it the next morning. Never realized as I just grabbed some cardboard and started working the next day. I kept hitting it on every small bump on the road though and finally actually ran my fuel rail into my firewall at lunch one day before I realized what had happened. Jacked it back up and remade it and it's still pretty low hanging fruit, but much better than it was.