The .30-03 case length = 65.0 mm
The .270 case length = 64.5 mm
The .30-06 case length = 63.35 mm
You can't neck down a shorter .30-06 case and create a longer .270 case with the same shoulder angle. That's why you have to start with a .30-03 if you want to make a proper .270 WCF.
O'Connor got it wrong, just like a lot of others, but he realized he was wrong after being corrected. He wasn't right about a lot of things where his knowledge was second-hand, just like today's people who buy the rumor 10th-hand.
