Dinny, you don't have to hot rod them, just use a faster burning powder. If not Unique, then Blue Dot or so, just something that developes the pressure quicker. Reloader 7 should be a good one, but go toward the higher loads. It still won't be a 'heavy' load or Ruger level, but it will develop the pressure quicker sealing the chamber and bumping up the bullet for you. If nothing else, buy a box of .454 cast bullets to try. I use a lot of the swaged lead 'factory load' bullets from Remington. You know, the ones in the 'standard' 45 lc factory loads. They are .454 with a small depression in the bottom and they bump up beautifully in my Colt SAA with oversize throats. I load them with 8.4 grains of Unique for the colt. They are fun to shoot, the accuracy is good from them, and they are still considered a 'full' load. I might get a little more accuracy from a cast .455/456 bullet, but I'd likely have to load them just a little heavier also. With the Colt, I'd just a soon not and these loads do what I want them too. If I want to shoot a 'hunting' load, I'll use a different gun.
So the idea is to try near max loads (but for the 'standard' 14,000 pressure) for your bullets or try a larger diameter bullet. If they will chamber, you might try some 250 gr bullets for the 45-70. My buddy had a mold for these that threw them at .456 and they shot great in the oversize chambers on an old EMF Dakota. Good luck with it. 44 Man