Being a rifle manufacturer i generally have two mind sets about chamberings like this. The practical point of view and the experimental point of view.
from a Practical point of view i really do not like improving the 08 class case. Why, you dont get much out of it……. I can hear it all coming now, i get 200 fps more velocity out of my 260 AI then a standard 260 rem gets……. Well, that may be the case but its not because the improved case design is allowing that much more powder to be used, its simply because the chamber pressures are being increased dramatically. Most custom chambers are cut to min spec dimensions and will of course handle higher chamber pressures then factory chambers.
in reality, when both are loaded to the same pressures an AI case based on the 08 case will produce 50-75 fps more velocity then its parent case. Is the fireforming chores worth that gain, for me no.
but then again you will hear, but, but, but i still get 200 fps over a standard 260 rem. Ok, with proper full power handloads, a handloaded 260 rem will get around 100 fps more then what is commonly stated velocity as well……. Again, when loaded to equal pressures your gaining 50-75 fps max.
next question comes down to caliber…. The 270 is a great caliber but is it better then the 7mm. Only if you like the 270 better then the 284. There is no bullet weight in 270 that can not be matched by a 7mm of similar weight, however there are many 7mm bullets that far out class the 270 options. We must look at he chambering however, the 08 case would be at its best with 130-150 gr 270 bullets. It would work OK with the 170 gr bergers as well but velocities would be cut significantly.
Going the other way, there are a host of 6.5mm bullets that will also do anything any 270 bullet will do ballistically. so i could argue why its not a good idea.
Now the experimental side of me brain loves oddball things. Simply put, if you want a 270-08 AI, get one and i am sure you will have many, MANY hours of enjoyment using the rifle. In the end, all of our opinions mean nothing, build what you want and enjoy it and report the results!!