Another way to load for wildcats is to extrapolate from data for similar rounds. In this case, the .270 Winchester would be the easiest, since there's abundant data for 140-grain bullets.
The laws of internal ballistics suggest that the 6.5/06 is capable of about 97.5% of the velocity of the .270 with the same bullet weights.
Most .270 data doesn't list 140-grain loads that get 3000 fps in a 24" barrel. Most list a top velocity of just under 3000 fps. Barnes, however, lists several loads that top 3000, the fastest 3050 (IMR4831), which translates to 2974 for the 6.5-06.
One faster possibility, though, is Accurate MagPro--though their data doesn't include a 140-grain bullet. With a 130 it lists 3234 and with a 150 a flat 3000 fps, which means that a 140 should get around 3100. That would work out to around 3025 in the 6.5-06.
