I'd not get my pants wadded over "optimal" twist rates. When I built my Whelen I had the choice of a 1-16" SS barrel blank for $40 or any twist I wanted for $225 and up. I went with the 16" twist because I was just a poor kid. It will shoot any 250 I've ever fed it into groups 1.5" or less and shoots the old 300gr Barnes Originals that I have a stash of into right around 1". Unless you're planning to shoot some long pointy 35 bullets that I'm not aware of any commonly available twist will work. 16" was about the only twist rate on all things 35 made in the US for forever and bullet makers know that.
If building from scratch and prices are the same absolutely get the tighter twist, but don't let it shy you away from a good deal on a factory or used custom rifle. It is a 35 caliber afterall and not a 223
