The 77SMK is reported to do amazingly well out of the Shilen barrel.
I generally run 75gr black hills red box. I don't think you can go wrong with MK262 as it's designed to be a precision load.
1/8th twist will be fine, especially if its a wylde chamber.
Honestly, whether its Shilen, Noveske, Krieger etc... you're gonna have a difficult time finding one to be better than the other.
I chose Rainier's Ultramatch upper because the upper itself is made to a higher standard.... and the BCG is also made to a higher standard. The PRI gas buster was a nice touch.
...Slow, deep breath in followed by two quick, shallow exhales, then one long breath out. It should sound like "HEE HEE HOOOOOOOOooooooo...HEE HEE HOOOOOOOOooooooo". Once your comfortable with that breathing pattern, try to sync the tempo up with your heart rate. "Lub-dub...HEE HEE HOOOOOOOOooooooo... etc". ~ CBruce