RE: 270-08?
Actually PO Ackley likes it very well. There are 3 very similar choices to look at for a wildcat short action 270.
A 270 Savage - Which is a 300 Savage necked down to 270 Bore.
270/257 - A 257 Roberts necked up, or 7x57 necked down.
270/308 - Necked down 308.
If you would like a short action 270, these are just about all you can build from, unless one of the new offerrings from Win or Rem cover it. However all the new Magnum's are pretty severely over bore, so maybe I should say the above options are the only ones in an efficient cartridge that will allow longer barrel life.
I would suggest straightening out the walls, similar to an Improved cartridge, when the barrel is chambered so you can gain that advantage as well.
From PO Ackley Vol 1
.270/.308 "This is a very fine efficient .270 cartridge made by simply necking the common .308 Winchester case to .270. It resembles the .270 Savage, but being slightly larger, it provides somewhat higher velocities, and these velocities compare very favorably with the standard .270 Winchester, and a multitude of the larger .270 cartridges, including the Magnums. The .308 necked to 7mm is quite similar to the .270 version, but it handles the heavier bullets at very satisfactory velocities."
.270/.257 Improved (Ackley) "The cartridge is the Ackley Improved .257 necked up, or the Improved 7x57 necked down to accept the .270 bullet. The same can be done with any of the other versions of these two cartridges, with similar results. Like the .270 Savage, this case is of lesser capacity than the standard .270 Winchester thus producing a more efficient cartridge. The standard .270 Winchester is somewhat over bore capacity and not as efficient as slightly smaller cases. Actually, the .270/.257 Improved produces velocities fully as good as the standard .270 with slightly less powder. It is a cartridge which can be highly reccommended for all types of American game."
In the data, the .270/.308 and .270/.257 are very close. 130 Grain bullet 3030 to 3130 fps, 4831 and 4350 powders listed.
The only downside I can see is that the chamberings being discussed are true wildcats instead of improved chamberings. So some time sizing brass would be involved. But that's OK, we need something to do on these cold nights anyway.
The 250/3000 Improved is on my wish list for a custom gun.