I'm trying to build a Mk11 mod 0 upper and a mk11 mod 1 upper for my SR25 lower receiver. I have both an Er barrel and a m110 barrel along with 2 kac uppers gas blocks and correct rails for each upper receiver. The only thing I need now is a recommendation for a good gunsmith experienced in working on Knights Armament SR25 rifles,installing the gas blocks, barrels etc. Any help is greatly appreciated.