I had a friend who used to have such a rifle and I can't recall if he made his cases from 270 or 30/06 itself. But which ever he used, it wasn't a big deal. So I don't think you'll have any trouble taking a 25/06 down to this cartridge.

I agree you want to lube your cases good before sizing down but be careful about really slopping it on the necks. Too much grease there and you'll get bad grease dents on the shoulder. Frankly, I use nothing but the spray on lube these days. Excellent lube and no worries about such things as grease dents etc. Just spray and size. Oh, be sure to get a little lube INSIDE the case mouth.

There shouldn't be a problem with this. You'll be amazed just how maleable brass is and what sizes and shapes a simple stroke of your press can do with it.

PS - Use a strong press...something like the RockChucker. It takes a little power to turn one case into something else. But just lube up a case and try one. Nothing to it.