As an owner of an APH, myself, there's a lot that needs doing to turn it into a Star Wars helmet. The originals were molded from one, so all of the surface details ended up softer. You're going to need to fill or cover the attachments for the air mask, there are holes on the sides that need to be closed off, the separations of the visor shield, its standoffs, and the helmet shell all need to be hidden, the slots for the visor slider knobs need to be closed...
But, that said, the vintage mics are quite hard to find. Elsewhere in this section is Fierfek's pepakura file thread. You can download and print out the mohawk pieces and scratch build your own from that as a template (what I did). You could look in the Junkyard or on eBay or Etsy for a vendor who sell visors and/or chin cups -- or kits, and ask if they'll sell you just a visor and/or chin cup. And several people offer decals. If you have a 3D printer, there are models out there you can use...
...Or for a hundred bucks you could get one of the amazing new Hasbro Black Series helmets and cannibalize what you need from it -- visor, mohawk, chin cup and strap, mic, plant-ons to cover the air mask attachment points...