Seriously consider the 6 Remington AI!
I shot the 70g Noslers at 4100 fps on a 14T, 26", 60g at 4400.
My reamer is zero freebore.
If you go 10 twist, the speed drops to 3980 fps with the 70g Noslers on the two that I Chambered at the same time, same reamer, both Hart barrels.
There is an issue with 8T barrels with high RPM's. The rotational torque causes the base to cave in. Around 3300 is the highest speed that I have ever heard of anyone being able to shoot a 105 with extreme accuracy. The base on those jackets were just not thick enough to take the rotational torque.
If it were me, I would try a 95g Nosler Ballistic tip with it's thick solid base and shoot for 3500 fps.
Two guys that I knew that built custom 6 AI's ended up shooting the 105's at 3150 with extreme accuracy, but you can achieve that velocity with extreme accuracy with a 6 XC...mine does it, and I have a node at 3250 with small rifle Palma brass where primer pockets lasts 8 firings, 31" barrel.
The 70g at 4100 is one of the ultimate coyote hunting loads that I have ever shot, bar none.
If you are wanting to sling the 105's as fast as you can, use this twist rate calculator to adjust your twist rate for the faster speed
https://bergerbullets.com/twist-rate-calculator/
Like I said, the extremes in rotational torque will cause the long boat tails to cave in. Also, I would not use a 5 R rifling twist when stressing jackets, conventional 4 groove and 6 Groove are easier on jackets.
