Think you're working on a cause that only a tinkerer would undertake. 600 grains is very heavy for a 45-70, let alone a 700 grainer. Even out of a Ruger # 1 with a generous leade, it would be hard to get enough powder in the case to give any degree of velocity. To accelerate a bullet with that much inertia, you're talking the potential of alot of leading, even at moderate velocities. I would think lube grooves should be there and be extra generous as well as an included a gas check. As a matter of curosity, what niche do you have in mind for such a heavy bullet?