Many thanks to all for the input. Your tips are valuable and will help with the project going forward.
I do have a stick welder, but if I'm not the worst welder on the planet I could certainly give the winner a run for their money. If this and all the rest of the sheet-metal welding is beyond my capabilities, I will farm out the work.
A couple of valid points Mr. J Par, and I get it. Part of the problem was the initial hunt for the Dart. I already had a complete 383, 4-speed, and 8-3/4 for the car before I found it. I figured I was going to find a slant car to transplant the drive train, or maybe a 273 car. Never in my wildest dreams did I think I was going to find a very affordable, running, 340/727 car, albeit still with the original 7.25 rear end. That makes the situation more interesting. Now that I'm the proud owner of a 340 car, I may decide a healthy SB is enough for my street-fun desires and the BB will move on to another owner. Or maybe I decide to do the BB anyway. Maybe the auto is enough fun and the 4-speed hits the auction block. At this point, I'm going to get this thing street worthy and drive it for a while to decide what I really want to do. I'm stopping obvious deterioration and keeping the car indoors while I sort things out. Some stuff it doesn't make any difference when it gets done. Like the lights, horn, heater, ignition switch, brakes, etc all don't work. I'm aware I will be somewhat inefficient by doing things out of order, but I don't want to start a looooooooooong project at the moment. Get it driving, sort things out, decide where I want to go, then finish the car. It is indeed the dream car, and it will be done right in the end.