Lee's 2nd edition deserves the criticism it deserves, he his a shameless self-promoter, but he's done some good work with cast bullets and the chapters he includes on alloys and hardness vs pressure are a must-read. He and Hodgdon did some work with bullet strength and they've included tables on cast bullets for just about every caliber that you might want to use a cast bullet.
"Ruger only" loads generally only apply to .45-70 and .45 Colt. Overloads are overloads regardless of the platform.
The
Lyman Cast Bullet handbook is the one book you need if your intent is solely cast bullet shooting. There are cast bullet loads in nearly every caliber imaginable, along with good chapters on things common and esoteric as regards cast bullet shooting. If I'm looking for a cast bullet load my first stop is the Lyman Handbook.