I shipped the BBL'ed action off to Shaw for a 24 inch, heavy sporter taper barrel in the standard 257 Bob. One of the other reasons for this project is that, in spite of the fact that I could load reasonably accurate reduced loads in the 270 for chucks, the case was less than half full and I recall most of the information from reputable sources claim that best accuracy is found when the case is nearly fully utilized- hence ruling out the larger '06 based options suggested here - I just don't need that much space.
So the path forward will be to work up some accurate 75 grain and 117 grain loads which fill the 257 case, as well as some reduced loads which will "nearly" fill the case (probably using 4759), bolt on a 3-9x, 4-12x, or 4.5-14x, depending on what my local gun shop has lying in their used scope case, and call it done.
Thanks all for your opinions.