Excessive heat in engine bay

[71 C20 CS]

I have recently completed the front end rebuild on my truck, including the engine and transmission. it seems really hot in the engine bay, but the temp gauge shows normal temps with the engine, even though I did get the crossover burn on the intake manifold.

The heat cooked my starter and I replaced it and it started to cook the new one, I put a heat shield on it and it fixed that problem, but now I'm getting vapor lock. The entire cooling system is new and the air was bled out, I don't understand why it's so hot, I've read rebuilt engines can be hot until they're broke in, could this be the source of the heat?

Any insight would be greatly appreciated,