If it goes to 220ish and doesn't get any hotter, and then cools down once you start moving you're probably OK. Rule of thumb is if it runs cool during normal driving, radiator size is generally good. If it gets hot when sitting idling then you have an air flow problem. you are not putting enough fresh air over the radiator when stopped. Bigger or more efficient fan, better shroud etc.

You are watching: Normal operating temperature for chevy 350


*

You say it generally stays under 210 - if that is during normal driving, i would look for a bigger or more importantly, more efficient radiator.I like to see 180-190 during normal driving, A/C on on a hot day. 200-210 when sitting at a light and then cools back down as soon as you are moving again.
*

Cross flows are definitely more efficient. There's still tons of argument about Cooper/Brass vs Aluminum. Factories went to Aluminum to save weight to help meet CAFE fuel mileage requirements not because they were better. It has more to do with tube size, fin count, etc. Copper/Brass dissipates heat better then aluminum but construction techniques with tube size allow Aluminum to work equally well under most circumstances, as long as you are comparing equal quality. Do you have a shroud with that puller fan? And is it mounted at he right place for the electric fan? An improperly placed fan in relation to the shroud can actually inhibit airflow! And yes pullers are better than pushers. If it's over 200 at 55 I'd be looking for a new radiator!
*

Here's fancy diagram of how the electric puller fan is mounted. Everything is kind of crammed in there, but it does seem to cool it better with the electric fan on.

See more: Is Brass A Pure Substance Or A Mixture Or Compound? Whether Brass Is A Compound Or Mixture And Why


*

There is a lot of misinformation about ignition timing and cooling. Retarded timing contributes to overheating. When the timing is retarded the spark occurs closer to top dead center. When this happens there is much more compression at the time of spark which generates more heat, causing the motor to run hotter, not to mention a loss of power. The loss of power means the motor has to work harder further causing a hotter running condition. Advanced timing helps cooling. Bump up your initial timing a few degrees and see if it helps the car run cooler. It's an check. Of course, if you advance enough to enter pre-ignition or detonation (pinging) you will start to overheat also. Detonation contributes to overheating. If you start to detonate back off the timing a little. Overheating cars should always run vacuum advance. Vacuum advance also helps cooling as long as there isn't detonation. It is also true that we can run motors hotter today then in the past. Radiators and colling systems are better designed to handle the increased pressure that heat induces. Part of the reason that lower temps were desirable in the old days was due to oil technology. Old oils broke down at much lower temps than todays oils which can sustain 250 degrees of oil temp before breaking down and causing a loss of protection.