Boated with some people last weekend, easy cruise and then pulled kids on a tube and one time when I stopped to pickup kid heard a loud valve tap, was valve train speed and oil pressure was ok. Lifted hatch and tried to figure out what side it was (couldn't tell ). Figured see what it did and after about a minute or two got quieter but present. About a minute later went away totally., it's a 5.0 SBC with about 1300hrs on it. Oil had about 25 hrs on it so tonight pumped it out, added a couple oz sea foam and ran it on the hose for about 20 moon and then changed it again. Should I start long block shopping?

With 1300 hrs???? It could be anything. It might last another 1000 hrs or it might blow up the next time you turn the key.

You could try running the next grade heavier oil, or some stp additive. Tired lifters can collapse with hot oil. I had that happen with an old high mileage truck. Popped the intake and threw in a set of cheap lifters and went another 140k miles before selling it.