Cars done 111000 miles but could running it daily with a leaking thermos or cap cause head gasket issues?The themostat housing are prone to leaking, about 60 dollar part at advance in USA. Very easy repair, 30 minutes.
Also check right side firewall wink valve that let's water exit from windsheild area. They are usually closed up.
Looks like engine has traces of radiator water in multiple areas leads to believe owner has neglected problem (themostat housing,) and added water, which turned to rust etc..
Buy a CSPG (cooling system pressure gauge) and anti freeze tester, you need both anyway. Both test will take only 5 minutes very easy to do.
Try to keep owner of vehicle in the dark cause they believe they have a blown head gasket. You will see pressure drop and light water spray around themostat housing.
Once confirmed themostat housing is leaking tell owner they have problems (they are thinking head gasket) then low ball them for trying to stick it to you.
Those are tough motors, 24-27 mpg.