It 'will' bolt on. The main differences between the G63B head and the 4G64 - none of the mechanical components will swap over. You HAVE to use the whole head and valvetrain (no biggie). The 4G64 is a hydraulic head minus the jet valves () There may be a difference in CC volume and I would advise using the 4G64 head gasket in the minute chance the G63B head gasket will encroach the combustion chamber area. Make sure the cam turns freely in the head before taking it (if the cam is seized that head will be toast) and expect to give the head a once over as it could've been sent to the yard due to overheating or blowing smoke (valve stem seals most likely and you already know what to look for in regards to cracks). Take the head bolts as well. Everyone re-uses them and there are weird things with Mitsubishi head bolts like different shoulder length/width and bolt length depending on the engine. Fingers crossed it'll be winner winner chicken dinner