yes im hopeful that I can(in a few days) rule out any long term damage that could have been ccause by the 'event'.
parked on the rather steep hill of my dridrive last night, and checked for air in the top of the system this am.
there was some air, although less than an eighth of the volume of other T connector. filled that and drove it up to temp. and reparked it... Will check it again in the morning.
interestingly, while slapping in some new shocks yesterday, I discovered a very slight dripping coming from the bottom line on the reservoir which feeds the heater plate(i think... can't remember at the moment) anyway, I tightened that up... only time will tell if it was the source of my slow level drop.
will update with progress of air check and pressure test tomorrow.

 

discoveries and results:
first pressure test, pressurized system to 17 psi.
heard a slight hissing, moved my head out of the way just in time for the lower connection of the hose that connects the lower hose assembly junction to the 45° nipple of the tstat to slip off the lower junction as gouts of sweet green spewed forth. discovered that all of the screw clamps of the lower junction assembly were too loose by at least 2 turns. tightened them all up, re blead the system and re tested.
2nd test. engine cooled overnight, pressurized the system to 17 psi, and after several hours the gauge read ~ 16.25. no obvious signs of leaks, and no sweet smell from exhaust. will have to see over the next week wheather lower hoses were the source of my slow level drop. if the slow drop persists, would that indicate the head gasket?

 

It can...but it could also be any hose, the throttle body heater, the machine, method of pressure you're using. .

I would run it...keeping an eye, bleeding it over the next couple days.

Coolant expands differently during the summer vs the winter. If anyone keeps a log, I have, you will notice some spillage or overflow in summer, then adding in winter.

 

 

So after extensive monitoring, I can safely say that no more fluid loss is occurring, even after a 500-mile beach trip weekend. temps stayed rock solid at 194 on the freeway and never broke 210 after long idling in the hot sun....My culprit all along must have been that poorly seated lower hose fitting, which I may not have found for a while had the (new-ish) tstat not failed.
in conclusion, I'll be adding a backup tstat in case this happens again.

Thanks to everyone who participated in this thread, hopefully, it will be of some use to someone in the future.

S