Ordered a new GII Lite Hunter ( I already have one, and love it, it is my medium to long range AR platform piece). The plan is to shorten the barrel on the new rifle to 16", (yes, I know they make a compact GII Lite Hunter) leaving the rifle length gas system, and enough barrel to thread to 5/8"-24, in order to install a flash hider / muzzle brake that accepts a suppressor.

Do I really need an adjustable gas block? I do not mind buying one, they just don't make what I want. I do plan to shoot mostly with just the flash hider or muzzle brake, but I want to be able to shoot suppressed, reliably, without tearing up the rifle.

I don't plan to shoot a lot of different ammunition, pretty much 7.62 x 51 NATO 147-150 grain. This is more of a close to mid range piece, I have a 20" barrel version for long range accurate shooting (one reason I'm doing it this way is to have two very similar rifles, so that most parts are common, making spares a more sure thing).

If I could find a two rail adjustable gas block, I'd just buy one and go on. But I can't find one. I may be able to make one, if necessary, from a regular two rail gas block. I have a preference toward my sights being mounted only to the barrel and the receiver, and I want a flip up sights and a laser on the short rifle.

I had my 20" G2 hunter threaded for my can.  I went with an adjustable SLR block and im glad I did, that gun is getting way more gas than it needs, mine run great on the 3rd click up from off without the suppressor.   Turning the gas down smoothed the gun out quite a bit, and it still reliable with and without the can.
 

You will be giving up a good bit of dwell time with the barrel chop so you may need the extra gas to cycle it.  

My factory length GII Lite Hunter runs fine, doesn't appear to be over gassed. When I bought it, we carried it out and ran 40 rounds through it just as it came out of the box. It was fine. I then bought a set of flip up sights, and a YHM gas block (I bought two at the Knob Creek show, DSA had them on sale a single rail and a double rail). I installed the double rail gas block and the sights, and it shoots just as it did when it came out of the box. I'm going to swap to the single rail gas block soon. It hasn't been shot with anything other than mil spec type 308 ammunition, it is accurate and reliable with it. Since it is a medium and longer range rifle, I will probably try some of the better quality ammunition with 168 grain SMK's, among others, to see how good it really is.

I like the rifle length gas system on a 308 rifle. So when I decided I wanted a shorter rifle set up more for close to medium range, I chose to buy another GII Lite Hunter and shorten the barrel, rather buy than the compact version. Especially since the barrel has to come off to be threaded anyway (we'll shoot the rifle as delivered for function and accuracy before we modify it). My concern is that the suppressor will push the gas pressure up to the point where it is hard on parts. Of course, that most likely could be cured by buffer and spring changes, but that may make it necessary to change those parts out when removing or installing the suppressor. I really want to be able to just swap the suppressor off and on without changing other parts, and still have the rifle be reliable and not beat itself to death. I am concerned that an adjustable gas block may probably be the only real good solution to that.