well it all depends on how worn these are.
SMG shipped some really nice ones but as the supply got low the kits got rougher.
you should need only a barrel and a lower as the m16 FCG can be de-milled to AR-15 type pretty easy, -- all you really need would be a ar-15 safety. -
-don't install the m16 sear--LOL thats a no brainer.
grind off the hook on the back of the m-16 hammer, grind off the tail on the disconnector , weld up or JB weld the back of the trigger with the ar-15 safety that should be all thats required.
you can weld up the m16 safety and use it-- i did that once-- lot of hassle for a $9 part--LOL
pre panic you could get 20" barrels from several places for $99, you can use a m4 16" barrel if you have a 750 FSB/gas block and a low profile .750 gas block for a under the handguards install.
on a kit this old -- you might want new gas rings for the bolt and a spring kit --all of which can be had quite reasonably.
this could be a really nice deal-- if the kit ain't too worn out or banged all to hell.
knowing CFS they could be all over the place