Ok what's your rap sheet look like. Be honest. And what state do you live in? There may be hope.
Just get a complete upper receiver group, you can go cheap, PSA and upgrade over time. But if you had the cash just get a DD or BCM or if money was no object get a Knight's Armament.
In my opinion, 18 inch barrels for an AR is eh, not worth the weight and length disadvantage, with training you can reach out to 300 yards with a 14.5. But if you insist on making an 18 inch Designated Marksman Rifle (DMR) then you have to get a bull barrel, and it has to be in stainless steel.
as far as a brake, I would go with
Experience the Hypertap® Muzzle Brake by Precision Armament. Over 84% recoil reduction, easy installation, and superior heat resistance.
precisionarmament.com
or something similar.
generally you want a four port muzzle brake because for some reason more than four ports doesn't add benefit and less ports don't provide maximum recoil mitigation. To further help with recoil, you can get a staged buffer weight and the thing will shoot like butter.
Binary triggers are weird. FRT are the way to go. same muscle memory. Had a binary trigger, very strange for me to shoot. Couldn't get used to the way it handled.
Back up sites are cheap add those and a good weapon light.