"point blank range"...
There's the friggin' problem.
Get a decent barrel sight (think ladder variant - Buffalo Arms makes a very fine one), regulate the load to it, and learn to use it.
Load a decent BC slug (400+ grains) in the .45-70 case now that you've lengthened the throat and action to have zero feeding problems, and go forth to slay stuff at range "point blank" can't even begin to contemplate.
