Thanks guys for your help.
It seems if i did just a little more investigating/tweeking on my own I would have the answer.
Investigating taught me the differences between the 284 and 308 were not as horribly drastic as I imagined.
handirifle was correct. Some tweaking of the lips netted me two in the mag and one in the chamber.
I'm calling that good enough for now.
For all I know that mag might not have digested 308W. Never tried.

FWIW I can fit four in the mag but #3 is positioned drastically different than #1 (first cartridge on the follower)
Seeing as I don't really believe in Zombies I've concluded I'll never see more than three at a time. Lifes not like the movies ya know.
Thanks again for your help. Just seemed silly to go ahead with load development on a single shot sporter :D