Its not a headspace problem if the bullet dosn't touch the lands- its that the leade or "freebore" is cut deep into the barrel. I wouldn't worry too much about trying to get near the rifling- if you seat the bullet too far out, you might not have enough bearing surface held in the neck of the cases causing inconsistant bullet pull. Seat the bullets at least .308" deep and forget about the rifling.

With a 165-168gr. bullet, I find that 4064 will give a very accurate load at the maximum load and approximately 2 gr. less than the maximum load.