My 6.5x47 Lapua has a 1 in 8.5 barrel at 28" in length and I'm using 37.5 gr Varget with 123 Scenars.
That's pretty much my exact same load but I run shorter barrels a 16" bolt an 18.6"semi and a 20" bolt. All work extremely well with this recipe.
Have killed deer at just under 500 yards with no issue.