When Is Hot Too Hot?

I took my car (68 Barracuda 340) out for a drive yesterday, the temperature here in Toronto Ontario Canada with humidity was around 95F.

With very high humidity, no doubt.

I realize these types of engines tend to run a bit hotter then stock to start off with

Not if they're built and tuned correctly.

picture below where the needle was sitting. Is this still considered an acceptable operating range

Yes.

Just incase, does anyone know where I can purchase a lower radiator hose spring preferably in stainless steel and available on this side of the border.

The spring is not needed -- it was to permit the fast-fill system in place on the assembly line. It serves no purpose once the car is off the assembly line; if your lower hose is collapsing it's because your radiator is badly clogged, not because you lack a radiator hose spring.