426 Wedge possible install challenges

I definitely would like to go OD. Which tranny do you suggest for this application? EFI swap would be a for sure thing. What do you mean by "matching the cam" to the cars specs? I have asked him for the TC and cam spec.
camshafts chosen for engines in big heavy cars may not be suitably matched to a lighter weight car, the torque converter matches the cam, which matches the gears, which matches the weight of the car. so you *might* need to change the cam and torque converter to keep the build optimal.

there is no "easy" or "cheap" OD solution and most all of them require some fairly extensive floor and frame modification. hemmed in by a big block, your options are even fewer. my back of the bar room napkin math pens out to something in the 5~7K range

EFI is affordable and accessible, if you're looking at a TBI style system. if you want multi port, and an ignition system that compliments it, be ready to cough up a bunch of dough.