Carb or Ignition issue?

A "small" head gasket leak can be put off repairing until better weather with a leak fix, not partial to any one brand, years ago did it with table black pepper, har.
If you go this route, main thing is follow the directions. Should be something like: (may first say flush the system) With the engine running, radiator cap off, full of water, thermostat open (you can see the water moving in the radiator) pour it in the radiator.
Put the cap on let run (or drive) x amount of time. Most important next, turn it off and walk away, over night if possible, allow it to cool. The repair product need to set up (harden) in the opening and hopefully seal it.
That said, a head gasket leak usually will show up if you have the cap off the radiator, top off the radiator, til it overflows the top of the radiator cap lip with it running and there is still that occasional bubble or more popping in the cap opening, maybe more the warmer the engine gets. No bubbles, probably no leak.
Be sure you have all the air out of the system.
And that being said, you drove it 500 miles and had to add no water. It is normal for a little bubbling at a fillup after highway travel. These engines can run a little warm. Does your temp gage run half way of the gage on the highway or around town?
It may be as simple as a stuck thermostat.
Bottom line, if the radiator does not act as though it has something inside trying to get out after a run down the interstate, and you are not constantly having to add water, you may have no problem at all.

It is actually 900 miles from where I live in Florida lol.

I normally add a little fluid every few months, like maybe 3-6 ounces.

I say head gasket leak because I saw a little bit of white smoke while at idle once the temperature started to drop.

I am trying to find a place that can weld up my EGR tube holes at the exhaust manifold. I temporarily just had a going from one end to the other and was suprised it lasted 95 percent of the trip!

I made a "pair tube block off plate" from a Simpson Strong Tie wire shield from Home Depot, under $1. That was several years ago, made it to fit right in, seals with gasket.

I used 14mm x 1.5mm wheel lugs from O'Reillys ($4.99 for four) to plug the pair tube outlets coming out the upper manifold heat shield.

I was able to get an exhaust shop weld some nuts in there for the low low price of $10.

I already had the upper ones closed off with some lug nuts. It was only the tubes ones that I needed to do something with. Really good price in my eyes!

Your white smoke when the temperature started to drop is completely normal. You should see up here, everything, including semi's have constant white smoke coming from the tailpipe, even air cooled engines. Its the moisture that is normally found in combustion that is condensing when it hits the cooler air, just like your breath.