Eagle has the cooling problems pretty well whipped, his advice has set me straight.
Only fill the surge tank about half full, with coolant (best with the motor hot). Most anytime you´ve done any coolant system work, you have to get the air out of the system. Filling the surge tank half full, gives the air someplace to go, that won´t blow much coolant out the cap.
Loosening the temp. sender at the back of the block works at initial fill, only to be attempted with the motor cool and not running.
Squeezing the top radiator hose, with the motor hot (be carefull of the fan), helps get some of the air moving. You can often see the bubbles moving into the surge tank.
Turning the heater on also seems to help, helps increase the flow to the surge tank area some, at least on mine.
Parking nose up and/or down and reving it also helps.
I´m sure someone else will chime in with some other techniques.
Temp. senders for the guage and maybe the guage itself are notoriously inacurate, at best an approximation. They measure the temp. at the top rear of the block, which isn´t necessarily what it is, at the thermostat or the front of the block.
Since installing the thermostat with the bleeder hole built in the stopper, I haven´t had much problem with air traps or blockages.
Smog test, first guess would be the 02 sensor. I had one that would lean out the motor at around 2000 RPM and the replacement would run real rich at idle, now I have one that seems to work well.