Bart, attempting to form .270 Win from .30-06 will result in a case that's shorter than the the intended length, even if it is still longer than .30-06. To achieve the proper case length (2.54", that of .30-03), you need to start with .30-03 or one of its full-length derivatives (.280 Rem, .35 Whelen, .400 Whelen, etc).
Most modern discussions of .270 Winchester will claim that it is based on .30-06. But, if you go back 30 to 50 years, you'll find descriptions of the cartridge specifically stating that Winchester's design work was based on .30-03. At the time of the .270's introduction, .30-03 brass was not hard to come by and .30-06 was a perfectly acceptable substitute. Plus, the longer neck gave Winchester the opportunity to advertise that it had a longer case than .30-06 (hinting, improperly, that it had more case capacity).
.400 Whelen and .35 Whelen were developed at essentially the same time as .270 Winchester. They were both based on .30-03, as well. They were able to retain a longer case length (closer to .30-06) with the '03 cases, than with '06 cases.
.30-03 may have been "old" in the early 1920s, but it was far from obsolete.
If "old" is the measure of how useful a cartridge is for wildcatting, we shouldn't have ANYONE messing with .220 Russian (PPCs), .222 Remington (multiple cartridges), .444 Marlin (JDJs), or even .223 Remington (.300 AAC/7.62x40mm WT), any more.
"Such is the strange way that man works -- first he virtually destroys a species and then does everything in his power to restore it."