I'd look at the 90gr. Sierra BlitzKings, they shoot great, and are similar in weight to your preferred TTSX, I'd guess the BCs are pretty close, too.
Sounds like loads of fun! My reservation coming from a long ago recollection of some early Blitzkings (albeit in .224 VS .257) was having some 50 gr versions vaporize mid flight when fired out of a 22-250. Not even making it to a 25 yard target 1/2 the time. I am wondering if they would hold up to 257WBY velocities. Wouldn't cost much to try 'em, I suppose, but I would have to look at how well they replicated the flight path of my TTSX's.
