6mm-280 is as close as I can get.
I'd get Hornady to make a form/trim die. It only takes one for my 6mm-280. It might take two for a 6mm-06 but that is something you don't have to be concerned about. Just tell them what you want to do and they will make something that works.I think the 6-06 is a myth I was unable to get anyone to tell me what dies they use to get from 30-06 to 6-06.
Buy a 2 die Redding type S bushing fl die set, run the 30-06 brass through it with a .291 bushing, then use a .272 bushing, you will likely have to turn the necks of 30-06 brass unless its winchester. It would be easier to run it through a fl 270 win die first. When you order the type S die set also get a expander assembly for a 6mm rem. This is how it was done before custom dies, and works just as well. Although a 240 wby still gets the nod, but is frowned on because you can't get "cheap" brass.