WOW! Thanks for all the comments and insight. I've been talking to a buddy of mine who is getting into molding his own bullets. He has a Marlin 45-70 with the 22" barrel that he's been using factor bullets on. He's cast for other calibers but not the 45-70 and just picked up a couple of different molds...we're going to have a little fun!
A little update - finally got out to our cabin and did a little shooting. Fired some JHP Remington 300's as well as a few of the Leverlutions. Had no chambering problems like some speak of with the Leverlution. Used a small 5" paper plate tacked to a big pine tree for a target and put 6 rounds into it. Then put a soda can ontothe tree with the bottom end out and hit two out of three on it...last one was a tad low. Only 30 yards, but with aging eyes and the stock open sites I was pleased. It's funny... I've always shot better with an open sight than with a scope. I assume it's the field of vision combined with my own specticles.

It's going to be a learning curve with ol big bore to learn how to reach out and touch something, after shooting the '06 and 300 Win Mag for a number of years... but with my friend loading them up for us, it will be fun.

Again - thanks for all the replies. I'm learning a lot!