I do serious restoration work. Heres what I'd do exactly.
Use the 180 (since it's handy, and will suffice) with my hands to go after anything rough or bad on the surface, i.e. Those weird ridges near the holes.
Pay close attention to the gloss of the paint. Use a Scotchbrite pad, steel wool, gritty tub cleaner, whatever, to go over the entire thing and dinge up the gloss so it's not so shiny anymore. That is the goal. No more than that. This is fast work with a Scotchbrite pad.
That's your prep. The ready-for-paint coating is a smooth (but deglossed) old paint.
Next I do a 2-cloth solvent wipedown in the new paint's solvent, also looking for any reaction between solvent and old paint, as that'll nix the deal. Then prime if needed and topcoat. Done and done.
The purpose of the scuffing is to introduce microscopic crags and fissures in the glass-like surface of the old paint. The new paint will flow into these, harden and interlock into them for a strong mechanical bond.
Niw if the piece were much more distressed, I'd use chemical stripppers and turn down the pressure in my media blast cabinet to blast to SSPC-SP10 near white metal.
Mix up a batch of whatever aircraft grade primer EPA will let me spray this week, dab it under the little hooks with a brush and let it dry. Then sand all the lumpy excess from that brush job, hang the piece and spray it with that primer. If topcoat couldn't stick to that directly or needed color assist, another primer: 2-pack epoxy barrier coat, til the surface is uniform, then many dusting coats of spray topcoat to good cover and flow-out.
