The shop that polishes my wheels also does the Jet Coating for my zoomies. I have had them do some street rod Jet coating that has worked real Good. The only limit I have found is the coated parts have to fit into a tumbler, you see when the parts come out of the oven, they are dull, so they need to be tumbled to get shinny like chrome. One of the best projects was our JrFuel driver had me Jet Coat his front bracket for the A/C water pump, power steering pump, etc on his crate motor for his 40 Ford, it looks like chrome, and he doesn't need to polish his chrome. Just make sure your silver High Temp coater has a tumbler big enough for your parts.
BTW, I have used chrome polish on my zoomies when a crew member let the engine cover fall onto the hot zoomies.
Have Fun,
Jon