Not sure on the lower by pass, but the upper one would be correct for trucks as long as the hole out of the pump is 3/4". Usually the by pass up there was seen on hi performance engines. Z/28s used the same water pump originally but they had a 1/2" outlet on top of the pump.
Will say its odd seeing on a quadrajet manifold as typically the intake would have a provision in the intake to have a little short by pass.
The carb could have been swapped at one point and they just wanted to make sure it was the same year carb.
Something tells me that the truck it was in was swapped to a TH400 at somepoint, probably at a dealer due to all the correct kickdown down stuff. Only thing that makes since most of the codes come up as a manual trans setup. The front pad was not stamped until the motor was assigned a chassis.
Here is a link to a little engine dress history, while its Camaro specific most of the plants operated the same.
http://camaros.org/enginedress.shtml