Well, with that info Id go with the bigger cam 222 @.050 and 107 LSA and the retainer/spring package from Hughes.

You wont be able to use the other higher lift cam unless the Magnum heads have been previously machined by somebody else or you for more clearence for .550 lift and above to be safe.

From what I hear, the Magnum heads are are definate great upgrade from the older heads for the SB, from the X, J, and the 308 heads. mike