Ed, The Factory Chevette manual as well as the Haynes manual say that the crankshaft pulley and also the timing belt must be removed.
Is the pulley what is keeping you from getting to the bolts. Both books indicate that the pump can be removed with the engine in the car after removing fan and the alternator , AC, and PS belts as well as the timing belt and it’s cover.It looks like the timing belt cover is in two pieces with one of them being behind the crankshaft pulley.
Ed , It was no inconvience at all. Now if I have to replace my water pump, I know to allow extra time because of all the extra complications. As is the case quite often on this forum ,one member’s problem gives all of us an opportunity to learn the solution and know just what we may be facing down the road.