Besides Bullseye powder what other powders do you want to try?
With the RCBS bullet 11.5 grains is the beginning of the yellow zone for pressure at 21,273psi. 12.4 grains is the beginning of the purple pressure zone. 13.6 grains is the max charge at 27,903 psi.
Here's what the 12.4 grains looks like
45-70 Govt - Bullseye - 425.jpg
With the Lee bullet 13.6 grains is the beginning of the yellow zone for pressure at 21,129psi. 14.7 grains puts you at the beginning of the purple pressure zone. 16.1 grains is the max charge at 27,812psi.
Here's what the 14.7 grains looks like.
45-70 Govt - Bullseye - 347.jpg
Not sure why the 14.6 grain chart is still showing up below in this post after I deleted it so just ignore that one.