Ok, so I know how confusing it can be to start a conversion. However, it's really not that difficult as long as you have all of your information. Here's my shot at offering an area with all of the collective information that you'll need for your conversion. If any of the more experience members care to chime me, please do. I'll add some pictures whenever I get off campus.
An assault rifle may not have any more than 10 foreign parts that are counted towards compliance.
Parts counted for compliance include:
Saiga rifles come with a total of 14 compliance parts. Which means that you'll have to change out at least 4. Adding a pistol grip puts you at 15, so I'd recommend just adding a US grip.
Some common US parts that easily count toward compliance include furniture (Buttstock (1), handguard (1), trigger control group (3), magazines (3)). Some of the other parts are a bit more difficult to change out.
I personally have a US trigger control group, grip, and changed the floor plates on my magazines. This leaves me with 10 foreign made parts
Items needed for conversion (basic):
Pistol grip, pistol grip nut and screw
Trigger control group AND RETAINING PLATE
-Size #8-32 1/4" screw for trigger guard
Bullet guide with tap and 3/16" drill bit (Dinzag offers these)
Something to paint the unfinished area after removing the trigger group (recommend Duplicolor low gloss engine enamel)
3/16" nylon rivet plugs (to plug those holes you now have on the sides of your rifle)
3/16" drill bit for drilling out the rivets on the stock TCG (and something to punch them out)
File or dremel for grinding rivets
Helps to have a drill press
(Notice this leaves you with more than 10 parts, include magazine floor plate for another easy compliance part, or just buy US magazines, or a different US-made lower handguard).
Factory parts that can be used for the conversion:
Lower handguard and upper gas tube (leaving them stock)
There's a spring you need to get from the original trigger group that isn't included in the Tapco set
Many use the factory trigger guard and secure it using the #8 screw mentioned earlier.
These are really all the items you need for a basic conversion. Here's a VERY good video on converting.
Now, if you'd like to put the traditional AK handguards, this gets a bit trickier. You can attempt to have the front site block and gas block pushed off the barrel to attach a lower handguard retainer to secure the lower handguard. A much easier alternative is to purchase a bolt-on retainer, like those offered at CSS (made from stock retainers) or from Dinzag (his own design). You can also fashion your own from an existing retainer, although I will say that this can be a difficult task, but definitely do-able. It involves removing some of the top of the retainer and the lever in it and replacing it with a notched #10-32 1" screw (this retainer has to be fitted on with a vise). I'd also recommend notching your barrel if you go this route as this is what is done on traditional AKs. You'll also need a gas tube fore the upper handguard.
That's all I've done on mine. Perhaps someone can chime in on muzzle brakes, etc. I'll have more time to look over this later, but I had a few minutes on my hands while I was up here.