A little hot for at rest engine, 185-190degF would be spec, with 190degF thermostat
Used radiator?
Did you do a Flip Test on it to see if there were any clogged passages?
The 2.8l did have a coolant flow design issue at the center of the heads so did get a hot spot, but with good water pump, so good flow, it wasn't a big issue, you would just get a bit of overheating earlier as water pump wore out or other cooling system parts started to get clogged up, vs say a 2.9 or 4.0l
In general an engine that heats up when stopped and at idle would be diagnosed with a failing fan clutch first, and worn water pump second
When driving the vehicle, vehicle's speed pushes air thru the radiator allowing for best heat exchange at radiator
When stopped the Fan takes over that job, it's not as good as driving but better than nothing, lol, so if engine starts to heat up when stopped it could be the fan is not pulling enough air thru the radiator, which means fan clutch is not fully engaging
Fan clutch has a bi-metal spring on the front, it is heated up by the radiator, not the engine, as it heats up it closes a valve inside the clutch which cause the fan part to spin closer to engine RPMs, so more air flow.
The clutch itself can fail, or center of radiator can get clogged up so bi-metal spring doesn't get hot enough for full engagement
After radiator/engine are fully warmed up, shut off the engine
Try to spin the fan, it should not spin, it will move but be hard to turn, thats engaged
Also pull the Fan shroud back and run your hand over radiator fins, should have a nice even heat, any cooler spots are clogged passages, no warm coolant flowing thru them.
Fan shroud is a VERY important part of the cooling system, fan can't pull air thru the radiator without it, it will pull it from the sides
Plastic radiators have been around a long long time, so 1980's would be possible.
Plastic rads are cheaper to make and for the most part last the same as metal, but metal can be rebuilt vs replaced when they get clogged up or leak, so more "earth friendly"
Manual trans radiators were often thinner than automatic trans radiators, so when getting a radiator always get the automatic version even if you have a manual trans, most 3rd party are automatic in any case since it will work on either