This sounds relatively normal. Black carbon spots or deposits in your coolant are better indicators of minor gasket failure. In the absence of blackness, I think you are fine.

Try flushing and refilling your cooling system to clean it out.

 

I do have some black powdery (like sugar consistency) substance mixed in w/ the coolant. Would that mean it's on the initial stages of head gasket failure? Is there a way the shops are able to confirm? Now, assuming that it is & the shop changes it with the new HKS head gasket & installs the L19 studs. Would that be sufficient for NA internals on my TN or am I better off looking to build the engine at this point? Sorry for all the questions, trying to assess my options (just in case).
Thanks ALL again!!!

 

Changing the studs is very involved job...labor wise. We would charge about $1600 for this. At that point, it might better to just build the engine.