Wolfe Pub. used to have Wildcat Cartridges Vol. 1 & 2. Maybe they still do?
Also for the technically minded Wolfe's Firearm Pressure Factors is interesting reading. Lots of equations, but still a good read.
JJ Donelly's Manual of Cartridge Conversions. Also Ken Howell's book on design & case forming is available again. Huntington's had it last time I looked.
I also like "Wildcat Cartridges vol 1&2" by wolfe publishing. Its a case design/cartridge conversion book. I found by looking thru it, that most of "my ideas" were done before. But its a nice reference.
Hey Maser, I think Happy Camper can hook you up with some wildcatting info. He had a killer load for an 8mm Mauser. 15 shots into one hole, must have been a secret load recipe.