I have been loading and shooting .45-70 loads made according to Spence Wolf's recipe since the mid 1980's. Follow his recipe and procedures exactly and you will duplicate his results. I spoke with Spence and his wife Pat quite a few times on the phone back in the day. You have to remember that Spence's goal was to duplicate the accuracy and performance of Frankford Arsenal service ammunition, NOT to find the ultimate match accuracy load for a single individual gun. The key features are powder compression to the depth that the bullet will seat so that the bullet is not deformed in loading. Seat and crimp in separate operations. Model 1881 500 gr bullet, with deep square lube grooves to hold plenty of lube (50-50 olive oil and beeswax was Spence's recipe and it works just fine. 1-20 tin-lead bullet. NO ANTIMONY, as this bullet design must remain plastic (deformable) to function as it should. Your Swiss is cleaner burning and maybe 10% more energetic than GOEX. Follow Spence's directions anyhow. It may shoot slightly higher at long range (say 200 yd plus) but you just tweak the sight slightly to compensate.
Shooting these loads is really a treat. With a blow tube to keep fouling moist, you'll be able to shoot till your shoulder is sore with no deterioration in accuracy from the Old Warrior. Get an original sight hood and a cast detachable pistol grip from S&S Firearms in New York, and it will feel like a nice offhand military match rifle.