This is what I have so far

[Nanawa]

Hello guys,

I wanted to show you all the parts that I have so far, is a mismatch between SA, WRA, IHC and other that I can't identify. I uploaded a couple of pictures with description of each one. I will upload more pics with more information about it.

[jak]

What you are calling the breech is actually the bolt. The one with cracked lug is junk and should not be used. The other is a Springfield bolt.
The gas lock screw with crack in the valve will cause problem. It will allow gas to escape and cause the rifle to short stroke. Since parts are rare in Paraguay, I don't know if you can successfully weld the crack.

[Orlando]

Do not use the cracked parts...................,they are not worth trying to salvage

[Nanawa]

The cracked bolt will be just a paperweight then, I might use the cracked gas block for display only until I find another one, I don't see any way to take it apart and weld it, or make a new one.

[Orlando]

gas screws are cheap, not worth trying to fix

[jak]

Nanawa lives in Paraguay. Parts are hard to obtain. That's why I suggested welding.

[Nanawa]

I might be able to buy one from any store in the US and get it here in Paraguay, the thing is we have a ban on importations of certain items, and one of those items are guns and gun related parts, hopefully that ban will be lifted soon.

[RDS]

Another solution to fix the gas plug would be to dissemble it and remove the valve and spring. Then a steel plug could be turned, inserted into the gas plug body and brazed, silver soldiered or welded in place. It would in effect turn the gas plug into a solid gas plug. I believe the gas plug is stainless steel so maybe the inside of the gas plug could be threaded and the plug threaded into place.