Building an F A L is fairly easy. Torquing the barrel and setting the headspace is the only "difficult" part of the assembly. If you have the tools to do these two things, it is an easy operation.
The advice that was given earlier about getting a StG 58 kit from DS Arms is good counsel. The StG 58 rifles were the very best F A Ls ever made and saw very little service with the Austrian Army. The kits are essentially new rifles that had the upper receivers cut up to comply with the Moe,Larry,Curly importation laws.
Speaking of complying with moronic laws, you will need to replace seven perfectly good parts with US made parts in order to comply with the 89 import ban nonsense.
Of the 20 listed evil parts, the rifle may not have more than 10 of them. Of the 20,the F A L has 17, so 7 parts from the list must be replaced.
The F A L specific parts are:
Muzzle device
Barrel
Hand guards ( both right and left hand guards count as a single part)
Gas Piston
Upper receiver
Lower receiver
Bolt Carrier
Bolt
Charging handle ( some simpleton at ATF declared that the charging handle on an F A L is actually an operating rod. It isn't, but there it is)
Magazine Body
Magazine floor plate
Magazine follower
Hammer
Trigger
Sear
Pistol grip
Butt stock
Replace any 7 of these 17 parts with US made parts and your rifle will be in compliance with the 89 import ban. The most common parts replaced are:
Muzzle device
Hand guards
Pistol grip
Butt stock
Fire control parts
If it were my rifle, and I were building an StG 58 kit, I would replace the:
Charging Handle
Gas Piston
Pistol grip
Upper receiver( DCI "Coonan")
Muzzle device
Magazine floor plate(s)
Hand Guards. (DS Arms Belgian style bi pod cut)