What have I got myself in to? Denver here we come!!

I agree. It is well known that a point close to stock, the 2 bbl throttle body becomes a restriction on Magnum truck engines. There are several "Fastman" type companies that make oversize 2 barrel throttle bodies. If it was me, I would use the Edelbrock intake, and spend the extra money on a 4 barrel throttle body. People swap 2 barrel to 4 barrel all the time, and while there is a bit of an argument for wet versus dry intake manifolds, I can't say I can remember anyone going from a 2 barrel intake to a 4 barrel intake, but then use an adapter to keep their 2 barrel carb? Why do it with the EFI setup either?