Sounds like a good plan!
A shift kit is a good idea. The tranny becomes much more positive, and lasts longer to boot. My accumulator spring is a steel dowl.
Sounds like you have excellent tune up parts in line, so you'll be good to go.
If you do have a mechanical top end, set the valves! It's important maintenance that doesn't get done properly, or with enough frequency on most vehicles.
Popular 2 bbl carbs besides the BBD are the Weber 38 DGES, Weber 32/36 DGEV and Holley 2300 350cfm. The most commonly used is the Holley due to price.
See if you can find the stamping on the block that I.D.'s the engine. It's on the top of the deck, just below spark plug #1. Probably a challenge to see in a van.
The good thing about the 727 is it's tough as nails so you aren't going to break it behind a slant. It can be done, but requires severe abuse and neglect.
CJ