340 exhaust manifold heat shield

I’m not paying 6k. Will go without.
Considering going without any gasket then. This will be on a rebuild. Was contemplating using a copper coat spray ( or even a copper silicone / rtv ) but concerned about the high temps at engine break in. Anyone done this? What was your experience?
One option is to brake in motor first without any and then pull the exhaust manifolds and do the copper coat. Any one do this?