I am early on in the process of building an m110. Not going for an exact clone but trying to build it right and hopefully make something that shoots lights out. So far I have these parts

Barrel -  https://nsarmory.us/nefarious-arms-m110-profile-barrel/

Upper/Lower - https://centurionarms.com/mk11-7-62-billet-receiver-set/

Trigger - https://triggertech.com/products/ar10?variant=31775057805430

will be getting a standard UTG  a2 style stock and a fulton armory BCG. The hardest parts are the handguard and gas block right now. My main issue is the gas block though since I am not particularly fond of the idea of dropping 350 dollars for a gas block does anyone know what the cost of having one custom made would be and who could make that part? Any additional advice for the build is greatly appreciated!

Since you say you aren't looking to build a clone, there is no way I would spend $550 for a Criterion barrel, when Lilja offers a stainless AR barrel for same price. My .308 with a Lilja shoots 3/8" groups.

I also prefer the Geissele NM trigger for a precision AR.

I'm not sure why you'd have to spend $350 on a gas block. There are tons of gas blocks for $100 or less that will do the job.

Kac gas blocks are 350 for the m110 style it's not a clone but I'm still looking to have a passing resemblance. A clone would be getting the correct stock bcg trigger and everything. Whereas I am planning to get the correct KAC handguard and a billet upper and lower from centurion but the rest is just going to be similar parts with a few upgrades like a trigger tech trigger. I ended up with the $550 dollar barrel because I'm trying to reach long range and nefarious arms makes custom barrels that came highly recommended to me for accuracy and longevity. Why do you prefer geissele trigger?