I have the same rifle with the same stock. Beware
: the front sling swivel stud is threaded into the wood! The wood screw stud only has a few threads making contact with the wood because of the ramrod space. I have read of some owners having their sling come loose and the rifle hitting the ground! Mine loosened up after shooting it from the bench with a short bipod. I epoxed a small rectangular piece of steel on the inside which was tapped for a machine screw threaded stud.
Be sure to torque the action screws then check them after a few shots. There may be some settling of the action into place.
Two friends and I installed the arrowhead breech plug in our Rem 700 UMZs and use BH 209.
We first used the 300 gr .502" diameter Thor bullet. I killed two cow elk in NM with this bullet. 60 yds and 280 yds. First shot exited, second one was an angular shot, the bullet was found after traversing 20", it had all its petals and weighed close to 100%.
Last year three of us switched to the 320 gr Fury universal bullet which are bonded. G1 BC is .260. They go into and down the bore easier than the Thors. With 110 gr of BH 209 my rifle chronographed 2196 fps. Have taken two animals with this bullet this season: a coues wt at 200 here in Az. Buck took a few steps and fell over, naturally the bullet exited. Also killed a cow elk in NM at 215 yds. Friend who was spotting the shot said I missed then the thunk of the bullet hitting the elk came back to us. My spotter saw the snow fly up after the bullet exited the elk.
Seeing you haven't found the bullets yet you may want to try the Fury universal bullets. Last time I checked Dennis had them available.
I just read about the new Hornady bullet. Sounds interesting. Let us know how they work for you at the range and when you get to hunt with this bullet how it performs.
Good shooting and hunting with your rifle!