Thumbs up for any bubbling requires strip to metal.
Most are Ali so will require zinc chromate etch then primer and flat out till nice n smooth then top coat with paint of choice,
I swear by HMG ,s acrythane product use it all the time with excellent results
Be patient and do not rush it, seen many good finish with rattle cans also , pre wipe everything with de Greaser or panel wipe prior to applying paint of any description
It's copasllip on the various top parts of the engine leg, I put this where I do not want any additional new paint landing
MY BIGGEST WORRY IS THAT MY WIFE(WHEN I"M DEAD)WILL SELL MY TOY'S FOR WHAT I SAID I PAID FOR THEM.