Will this bore clean up, magnum head content too.

Think i’m gonna try to polish up these bores a bit with some wet/dry sandpaper on a three prong hone and a little water. Forget where i saw that but seems worth a shot. Rings seated just from degreeing the cam supposedly.
That’s more likely to bell the bore than help anything. A proper rigid hone is the only thing that will correct geometry. Have you measured for diameter and bore taper with a proper bore gage?