There's some guys in here that know quite a lot about FEMA stuff. I ain't one of them. But, if I may, FEMA 353 is NOT a code. Its a document of recommendations. The committee that created the doc doesn't even exist anymore. And its been awhile but if I remember right there ain't much in 353 about specific fillers at all. Its pretty generic and QA oriented. The filler stuff is in 355 and is predominantly FCAW.
Also, this stuff can be downloaded for free. If your planning on using it, or if someone is requiring some of the recommendations I would recommend getting a copy or copies. 355 especially has some excellent information.