Keep in mind, the thermostat only controls the low end of the eng temp.   If the engine is running at 205, it doesn't matter if the stat is 160, 180, or 195.  Once it opens at those temps if the engine get hotter that is a function of the heat produced and the cooling system.   But if the engine wants to naturally run cooler that the stat temp, the stat will stay closed untill that temp is reached.

I replaced the stock rad. in my '79 last year. I now have an aluminum rad. and use a 180 t-stat.

Ever since it now runs at 160 degrees all the time. In the warmer springtime, the hotter summer and then the cooler fall season it always has stayed at 160 degrees.

Is this too cool or am I ok?

160 might be a little too cool, IF it is actually running that temp. I'd wanna verify it with an infrared thermometer, or a mechanical gauge. Your electric gauge/sender might be reading a wee bit optimistic. Our Sharks, with the exception of the '82s, really work best at around 180*/190*.
It's hard to believe the engine is really running that cool. Your t-stat is rated @ 180*...IF the engine temp IS actually 160*, then the t-stat would never open, which means there is no circulation of the coolant, which means the engine will overheat, which means it would be much warmer than 160*.
Does that make sense? I think your temp gauge, or the temp sensor might be lyin to ya!
My '74 always runs right around 185/190...I've never seen the gauge go any higher for more than a  minute or so...with the A/C runnin, in traffic.(yes...I HAVE driven it in traffic!)

You'll have to ifn you go to the gathering in the spring!

Thanks for the rundown, Joel!

For now I'm thinkin' "if it ain't broke......"

(C'mon Springtime!!!)

Yeah, as long as its running OK, DON"T MESS WITH IT!