I have gotten what I think are good results with a middle of the road load using IMR 4320, and the Speer 140gr in a 1917 Swede long rifle.
Have not grouped it, but the only way to miss the 300yd gong (with the sights set all the way down) seems to be to look the other way when you pull the trigger.
Remember that the 6,5mm Swede is a ~45Kpsi (max) level cartridge due to the old rifles still extant. (I have an 1897 Krag in 6.5x55 and won't push anything "hot" through it, or through my 1917 swede).
As much as I love the Swede, if you are building a modern rifle, and "looking to see what you can make happen", I don't think the Swede is the best choice.
You probably want top end performance, and in a modern action you can run 50-55Kpsi rounds easily. In a modern rifle, you CAN do that with the Swede case, but I don't think you SHOULD do that with the Swede case, because of the (remote??) possibility of that ammo finding its way into a weaker action.
Better would be to use the 06 case (or something else that floats your boat). The 6.5-284 or the 6.5-06 would allow maximum performance at full modern pressures, and neither can fit into an antique Swede rifle, even by accident.