LA w/ stock valve spring magnum heads - maximum lift

Check out magnumswap.com
They don't have any cam recommendations, but they say that the rumor of ~520 lift max is false. There running a cam close to or over 550 lift iirc. But the original springs are junk, as they barely keep up with the stock cam. so springs are probably going to be a must no mater what cam you go with. Better safe than sorry. Jm2c.