Looks pretty simple, A2 grip and stock, picatinny gas block, 20" barrel and a quadrail. Quadrails are a bit antiquated now but I'm sure there are some around.
Aero M4E1 enhanced upper has very similar angled sides as M110, and is my favorite upper to use, it's not milspec but a beefed up version of milspec that works perfect with quadrails. I would put that on an Aero lower, you can order the upper and lower from Aero with the cerakote of your choice.
I don't know if Aero makes lowers with the ambi slide release though. I think that could be added later. Ambi safety should be easy.
Aero no longer makes a full quadrail but they do have a gen 2 quad that has some of the more useless picatinny rail milled off. If you do get a M4E1 upper make sure your handguard fits on the non milspec upper.
And if you do get a M4E1 upper and are dead set on a full quadrail but cant find one I may be interested in a trade. I have an Aero full quadrail, I forget if it's 13, 14 or 15" anodized black I am thinking of replacing with a Mlock or Keymod. My quadrail is long enough you could have it cut back and a small section of underside rail cut back like the M110, then cerakote it to match the rest of the gun.
M4E1-
https://aeroprecisionusa.com/upper-receivers/m4-m5-enhanced-uppers/l/ar15.html You can find their lowers on that site as well.
Gas block-
http://www.surplusammo.com/products/saa-...-block-750.html