Martin, I hope it is turning out to your satisfaction, I wish I had seen this thread earlier. Was the rust treatment system you used a urethane that will permanently seal the metal before the POR-15 putty was applied? Kent at ************** likes Miracle Paint for this, then he uses Bondo brand "short strand filler" which is a two-part catalyst mix (not the stuff we typically think of as Bondo that sands off into pink powder and contracts/cracks over time) to smooth or fill any gaps. Sometimes the Miracle Paint actually "fills" in a little bit and smooths over the surface, and can be sanded down/reapplied as necessary.

The original 040 may be a single-stage (no clear coat). The advantage, while clear coat is an extra layer of protection, is that you don't ever have to worry about peeling clear coat or sanding/buffing through it. When you compound the single-stage, you'll have some color residue on the pad/towel.

It looks like you picked a system/path and got it figured out. I also have recently used automotivetouchup.com brand spray, which is an exact match to my body color (and metallic at that). They automatically include a clear coat can, even if you don't need it (maybe save it for another purpose), and offer primer as well (I'll use it to paint the inside of my Euro light housings to match the cladding). They also have an add-on spray trigger which makes the can more controllable. It certainly wasn't as fine as an Iwata airbrush, but with tedious masking and "feathering" I was able to "blend" parts of the engine bay where I performed extensive rust remediation. The casual observer would not have a clue.