Are my headers cooking my PS box?

I wouldn't worry about it. Yeah headers are hot, and it looks close but they dissipate more heat faster than the cast iron manifold simply because of the thinness of them. And that heat is also spread and dissipated among the whole length and tube by tube.
This is why people who own motorhomes and hard working trucks that tow often, prefer headers exactly because of the way they shed heat. And that breeze created by driving thru the air, dissipates and carries away that heat faster, so the engine compartment actually runs cooler because of them.