Well if I was forced to primer over an existing finish like that, I would not use heavy applications of epoxy primer. Use 1 coat of reduced epoxy over the bare metal spots, and use regular 2K urethane after that.
The problem I have repeatedly had is that 2 coats of curing epoxy become a barrier to the solvents that are absorbed by the underlying substrate, causing it to be released well after the job is done. This can cause ringing or edge mapping of the finish.
Thin applications of epoxy seem less likely to have this problem. 2K urethanes are more porous than epoxy and will also let solvent out more readily.
Now, for pure bare metal, there is nothing better than two wet coats of epoxy.
I would get water based wax and grease remover, because it cleans the metal better than solvent base. I know that seems weird. but it should be OK with DX330, if you are not too worried about having maximum adhesion and minimum contamination.