Thanks for checking in Xero.
I did get the water pump changed without removing the manifold or separating the pipe from the manifold. I assembled the pump to the housing prior to installing on the car. In order to get the assembly installed, I needed to remove the shift cables (manual transmission) and bracket to make room for the bracket on the pump housing that attaches to the engine. I'm sure the manifold has to come off if you intend to use a torque wrench.
It was funny. I called a GM garage to find out what it would cost to have the water pump changed, knowing full well I would change it myself. The guy rattles off the top of his head, that'll take about an hour and a half. I told him to check his book. He asked why. I told him this was the difficult engine. He had someone look it up. The estimate was somewhere between $800 and $900. Boy was I dumb. I should have said "Schedule me, have the estimate in writing, and I'll have the car in this afternoon!!!"
Four weekends later and about 50 manhours between my dad and I, we had it done. I probably spent an hour or more jacking the entire car up and supporting it so I would have ample clearance. I spent more time loosening exhaust hangers in case I wanted to try removing the exhaust and manifold as an assembly.