The winning actions in ELR competition aren't repeaters. There's a choice to make there - picking that feature for a fun rifle comes with a bit of a consequence for a competition rifle.

You can find a repeater action for the big magnums. Pierce, Desert Tech, Cheyenne Tactical, Cadex Precision, Stiller, and Barrett all make repeaters big enough for a 375 Cheytac. The magazines I have seen have 4.6xx" internal dimensions, whereas my loaded rounds are 4.760" with 400 grain Lazers. Following what is winning (by an absolute landslide), the Cutting Edge Lazer is the bullet to shoot, 400 or 425's in 375CT - BUT... you COULD get away with a much, much shorter cartridge length if you shot A-Tips. The Manners LRT2 is made for solid bottom receivers - not sure if Tom will make one in a repeater or not.

Where it my money, building a repeater, I'd buy a Pierce 10x and if Tom can't do a repeater for the LRT2, I'd drop it into a Cadex chassis... But... if he really wants to have it be competitive, I'd go solid bottom action in a Bat or Pierce in a Manners stock with a Bartlein or KP out front.