Interesting... first time I've seen the front sight placed like that, neat. Anyways, you can definitely build something pretty much spot on, short of the rail/upper as you said.
Thought I'd throw in a pic of the Colt L119a2's for comparison
Dug around out of curiousity but couldn't find any info on that specific rail/upper. What it looks like is one of colt's rails/uppers with part of the side rails custom milled off. If you get a similar quad rail and have access to a mill you can just mill off that area and viola, similar rail.
If thats too much work, a KAC URX3.1 might be a close second (although the lower rail is slick as well, unlike that rail). Parallax tactical has a rail that's sorta similar (but at the same time, not really).
Everything else is easy enough to find, hogue grip, asap plate, bad lever, moe ctr, afg2, peq box, xps2, flip magnifier, enhanced charging handle latch, flip iron sights and an interesting QD suppressor flash hider of some sort. Definitely an interesting one of a kind build.