From Galil Build ?'s
Get a can of Adrenaline Rush or Red Dog, drink it...Then cut a shim out of the can.
I've done it successfully with FAL's, the metal is so thin and compressable it shouldn't interfere with headspace enough to worry with.
I have over 5000 rds. through an FAL I did that way and zero problems and thats a 7.62x51 round.
Try it, if it doesn't work and headspace ,you are out $2.
Also the Izzy gas tube length and piston are different than regular metrics...The sights are also lower, both front and rear on the Israeli model. Gunthings.com can set you up.
Hope this helps