I think I've posted on that subject before. It's easier to say what you can keep

To stay non-restricted you can only try to duplicate the Galil Sniper or ARM because of barrel length. If you are ok with a restricted version, remember that you can't cut a barrel below 18.6" - you have to get a new one made...
You are better off starting with a hunter. M78 has that heavy barrel that I don't believe fits in the Galil handguard (cutting that barrel would be a shame too while the hunter is already at 20" - matches the sniper version).
Looking from the back of the rifle:
A Galil stock won't fit. You will need a stock and an adapter to make it attach.
You will need a receiver cover with the rear sight - either a galil or a valmet one will fit.
You will need a recoil spring guide rod with a latch - a galil, valmet or even ak one will fit.
You will need a galil bolt carrier or butcher the original bolt carrier to make it match the galil.
You will need a galil pistol grip and trigger guard
You will need a galil, valmet or even ak trigger
You will need a galil selector
You will need galil handguards
You will need a galil or valmet front sight base (keep the base/gas block - it will fit unless you want the bipod - then you need the original gas block)
You will need galil handguards and mounting brackets
Here's a diagram
https://iwi.us/iwi/media/products/GALIL_5-56-1.jpg
You can keep the receiver, bolt, barrel (need to thread and possibly cut), and gas tube maybe the gas block if you don't want to have a bipod