I have built several FAL's and am thinking of building a g3. I am looking at the parts kit, flat top reciever, and US parts kit at FAC. What is required to put these rifles together? Is there a step by step of how to assemble these guy's on the web somewhere?

It depends on the receiver type you choose.

The steel receiver requires you to weld the trunnion into the receiver, the aluminum receiver requires you to drill two holes into the receiver/trunnion to pin the works in.

The basics to the build are to start off with a parts kit, and remove the trunnion/cocking tube from the cut receiver. If you are changing the barrel out, then you will need to press the cross pin out to the trunnion, then press the barrel out. On the new barrel, check the chamber, then the headspace (not carrier gap).  Once the barrel/chamber checks out, press the barrel into the trunnion using the bolt carrier to check carrier/bolt gap. Once the gap is correct, drill the cross pin slot, then install the pin.  From there you need to jig the barrel/trunnion/cocking tube into the receiver and weld/pin.  From there, you laser the barrel bore and install the front sight in plane with the bore, then solder the front sight on and drill the cross pin slot and install the front pin/sling eyelet.

Even if you are going to just reuse the barrel trunnion, it’s best to pull the front sight and re-install after you have set the trunnion into the receiver.  If you don’t reset the front sight, chances are the sight will be cocked (different alignment in the new receiver than the old receiver).

The trigger pack/housing will need to be modified to remove the auto sear/holes, then a spot weld to keep the trigger from going into the auto position, then a grip housing tabs clipped and a shelf added/welded to work with the shelved receiver. Include changing out parts to USA parts to get the correct part counts and that about it.

Unlike the FAL, which only requires you to index the barrel, head space using the correct locking shoulder (cross pin), and install USA parts and a semi selector, the G-3 clone requires a lot of machinery and modifications to get them up and running.  

For the money, your better off just buying a built clone verses gearing up to produce a single rifle.

Better yet, instead of an unknown clone.  Have Jayson at IGF build it for you.  I have a SW5 that Jayson built.  NO FTFs or FTEs due to the gun in over 5000 rounds.  Still looks brand new.