falfiles is the best place for FAL info of all types. Only build a FAL on a DSA, Imbel or Coonan receiver. Imbel harder and harder to find. DSA, IMHO is the best but like most things in life you get what you pay for. Kits are also harder to find and going up in cost for decent ones. These days its worth buying complete FAL's rather than building them out of parts. Look around on the EE here and on the FAL files and you can see some good deals if you are patient. I found a NIB DSA STG58 for $750 earlier this year. YMMV
If you are going to buy one DSA is a good first stop and so is Enterprise. Many custom builders still build great rifles like ARS, Azex, CGW, ORF all good reputable builders.
Avoid Century FALs, have any WECSOG FAL's checked out before shooting.
Just my opinion, hope it helps.