Just remember, what works in another rifle, even an identical model, doesn't necessarily mean it will shoot good in yours. I prefer to choose a powder and bullet combo that shows promise from others that have worked with em, like you have with the RL-7, and work up my own load. A prime example is Paul5388's hornet load, it shoots good in several other member's Handis, but mine hates it.
In my .45-70 Ultra, I shoot 300gr nosler partitions at just a tad over 2400fps, but I started my load work well below that level and worked up, it shoots into less than an inch at 100yds.
If you choose to shoot levergun loads, I'd do some recoil prevention up front for the bench work, weight in the stock bolt hole, a better recoil pad and shoulder shield, and try to shoot as upright as possible which means either a high bench or high rest.
Hope this helps,
Tim