When you start talking FALs now you're talking
What is pretty much agreed to as the standard book on the FAL is The FAL Rifle
by Blake Stevens
from Collector Publications. It's not cheap, currently runs $US 120-130. I've had my copy for several years now. Also get the manual for it.
As to which version to get. The most desireable is one of the original FN versions; 50.xx (i.e. 50.63, 50.64). These are commanding serious money nowadays though. $3500 is becoming a fairly good deal apparantly. I've seen them going for upwards of $5K
. Now this is for the real deal. For under $2K you can buy a complete firearm from one of several manufacturers (DSA, Entreprise, Hesse, DPMS). For under a grand you can build from a kit or buy from Century. StG58 kits are available and several companies make upper receivers. All the listed companies also make uppers (the serial numbered part).
Beware though as some of these companies seem to have a QC problem and turn out substandard products.
To get info from the real experts visit the falfiles message board at www.fnfal.com.
Some of those guys forget more about FALs in one day than I'll ever know.