Ed i've used USC and Evercoats Metal 2 Metal. It is basicly aluminum powed in expoy resins. I've never tried powder coating it.
First word of caution.....if the product has been on the shelf too long, it's junk. I never could find out if they had a date code. But when first opened and its not soft and stirable, (like plastic filler) take it back! If buying at a parts house, open the can at the counter. I've had some cans that were rock hard😡
Second.. if it doesn't feather out nice when sanded, (flakes) grind it back off and try again. Don't try to recoat over it, your waisting your time.
Third.. it's real picky on the mix ratio. If it doesn't set hard by at least 45mins after applying, grind it back off and try again.