A quick peek at a minimum twist rate chart shows that the 1 in 14 barrel will stabalize bullets up to 300 grains, the 1 in 12" up to 340 grains. Not something a guy is liable to really need in either case. My Model 673 Rem in 350 Rem Mag shoots well enough for me with factory 200 grain core-lokt bullets and a 1 in 16" rate of twist. Even moving up to handloaded 225 grain partitions I expect to keep the 5 shots into 1.5" that the rifle has proven capable of. If this were my rifle, I think I would go with the 1 in 14" Shilen barrel. Why? It is close to what has proven successful in another rifle, and I like Shilen barrels. If you prefer one maker over the other go that route, if you need the extra $20 for scope caps or somesuch, let that make the decision. I have a nickel I am willing to wager you would not notice a different if basing the decision on the rate of twist difference between the two barrels.

Congrats on the new rifle. I am also fond of the under rated 35 calibers