Will seating them at 2.700 put you near the cannelure?
BL-C(2) is a fine powder for .308 - you don't need to ditch it just because it isn't in the Hornady book for that particular bullet. Other data for 150gr jacketed bullet is safe to use as long as you start 10% below max and work up. Metallic cartridge loading data isn't a strict "recipe" like shotshell data is, and OAL is not absolute. What fits the rifle is what is important.