water pump ok ,radiator ok engine still overheats

Hoses look or feel okay? Nothing collapsed? Do you see coolant flowing in radiator? Watch as engine hits operating temp and thermostat opens, you should see coolant get sucked down in rad. If not check thermostat. Hoses should feel pressurized and not soft, spongy, bottom how should have a spring in it to prevent collapse, but if it looks like it is collapsing then rad flow is bad. Check coolant for presence of hydrocarbons with a product called Block Tester - $50 to buy, or you can rent the setup for half that. If it tests positive you have a bad head gasket. Be sure to check oil for and coolant contamination, oil filler cap for milky or frothy appearance. BTW, radiators can be tricky - they can appear to have good flow when in fact only a portion of radiator works, a thermo camera can reveal how much of radiator surface actually functions or just feel across it. colder spots mean plugged tubes.

If, after checking all of the above your engine still overheats, try opening / removing the coolant circulation port(s) to verify coolusuallyant is entering and circulating throughout the engine. The port(s) are small bolts located on the engine block / head and sides. Maybe 1, 2, or 3 per side. When unscrewing the drain bolt hot water should squirt out if the engine is running; drips if engine off. Good Luk

If you have the 289 engine and it has been bored out past .040", that can cause overheating issues due to the thin wall casting of the cylinders.