You can go wrong with either one in my book. Garland Gilbreath built a 338 Norma for my brother on a TRG-S M995. I believe the mag box on those actions is limited to a COAL of 3.700, so if a repeater with 250+ gr bullets is what you're after, there are better choices.
The Weatherby "boomer" .580 bolt face case mag boxes will measure up around 3.815, so you can get a pretty big round in there as a repeater. I like the Mark V actions, so that's my vote for you.
338 Excalibur built by a Master Smith who frequents this forum.
338 Lapua Ackley Improved built by Joe Starnes
30-338 Lapua Improved built by JE Custom and Lone Wolf Stocks
338 Lapua (SAAMI) 10.7 lbs as you see it (minus bipod) built by Straight Shooter Supply