Difficult proposition - Relatively new bullet with Relatively new powder.
Start at about 50.4 grains. An Article by Richard Mann from Handloader Magazine recommneds starting at 5% below the MINIMUM charge listed for IMR4350 when developing loads using RL17 - in the case of a 30-06 + 165/168 grainers, this would be 5% below 53 grains of IMR 4350. Increase the load until your velocity is 50-100 fps faster than the velocity for IMR4350 - again, the recommendation from Mann's article on RL17 (i.e., 2832 fps +50-100fps) or when you see pressure signs (however, these are not reliable with RL17 - often appear after pressures well above safe limits).
Interesting, applying Mann's recommendations to data for Barnes bullets (another monolithic)would give you the same recommended starting load of about 50.5 grains OR 50.35 grains to be exact(Min load for Barnes 165/168 in 30-06 with IMR4350 is 53.0 grains as well).
Hope this helps
