I'll just do a .015" taper and 35 degree shoulder.
I have 3 6.5-300wm's now but the sizing above the belt is getting tiresome, even with RWS brass, as well as trimming because the of 25 degree shoulder. So I'll probably rechamber them to 6.5x68 Imp. when the barrels give up. I have 3 7-300wm's too but I don't shoot them nearly as much so they will last a good deal longer. I have a bunch of 300wm RWS brass but have been shooting Winchester for a bit to get the additional velocity in 2 of my 6.5-300wm's. They shoot 140's 3300fps and 123's 3500fps in Winchester brass. In RWS brass I get 3230fps and 3385fps. The RWS brass is the toughest brass I've ever used and I've used every major brass manufacturer there is so it would be nice to use it and still get some good velocity. The additional capacity over a 6.5-300wm will make it where I can at least get the velocity I get using Winchester brass but using the better RWS 6.5x68 brass and not have the sizing issues. The down side is the additional cost of a bolt, dies, and a new reamer. I guess I could always do a 6.5-300 Norma Imp instead with 423 Dakota brass.
I might have to do a .270 cal too. I haven't built anything .270 in probably 15 years so I might have to try it out again.