Might consider flushing the cooling system, especially the rad. If you see a buncha crap in there, flush the heck outta the rad. If it were me, I’d look at the coolant in the res, if it’s the cheap green stuff, switch to Zerex G05, flush the block and rad with a garden hose. Dump a thermostat in for good measure.

Water pumps on these cars are pretty robust. Possible, but lower on the list of causes