A cam that worked pulled strong in my 12:1 340 was a sig erson solid flat tappet. 258/258-.580/.580-107 in at 107. I had a 4 speed at the time with 4.10 gears.

http://www.youtube.com/watch?v=aIxaesJ190U

http://youtu.be/lCZAaN7fFLg