Sam.
Don't sweat the light barrel. I just went down and measured mu 30" crescent butplate Hartford I ordered with the standard weight octagon barrel. It measures 1.020" at the action and just .900" at the muzzle and it is a fine shooter. I had the tang sights on it one day just to see what it is capable of at 200 yards and I covered five shots with three fingers. With the barrel sights I put 3 out of 6 shots in the white plate fired at the buffalo up on the hill at Raton and managed to hit the 1585 yard iron buff using the barrel sights.
That short light barrel points hand holds well off hand.
I think the Lawrence sight might reach a mile from what I had left over on the staff with out having to use the top notch.
With your ROT you have a wide field of bullets you can use in that rifle. I will be waiting to see how the GM barrel shoots for you.
When you feel you want to try some of the prolate and elliptical bullets I shoot in the 1/17 ROT let me know and I will make a package. These two shoot very good in my 1/17 twist. The two outside bullets are the .44's. The left is the 500 gr Elliptical and the right is the 485 prolate.