I might have something to help. Although the heaviest data I have is for a .500 gr. bullet. If you reduce loads by 10% and work back up slowly and carefully you should have no problem with this data using your 525 grainers. just steer clear of the stated max charge
All of these loads were worked up and tested in a stout ruger #1 However they are pressure rated level 2 handloads and are deemed safe for the M 1895 lever action.
RX10X= start @ 37.0 gr./1508 fps./ 26,400 psi.
max @ 39.8 gr./ 1604 fps./ 32,600 psi.
Benchmark= start @ 38.0 gr./ 1417 fps./ 25,200 psi.
max @ 41.7 gr. / 1545 fps./ 33,500 psi.
BL-C2= start @ 42.0 gr./ 1279 fps./ 20,700 psi.
Max @ 47.0 gr./ 1784 fps./ 34,300 psi.
Once again, these loads are for a 500 gr. cast lead bullet in the .45/70 cartridge. You should be able to use them as a base to work up a load for your 525 gr. bullets. Be sure to reduce your charge 10% from these loads and work back up. STEER CLEAR OF MAX!!!! You may or may not be able to load them into the tube magazine at length. Im not familiar with those bullets and Im not sure of the C.O.A.L. Just be careful and use your head. I have had my best luck using cast bullet loads at level 1 pressures in my .45/70 rifles and I would be willing to bet you will find your best accuracy there as well. Good luck...