1993 cb400 super four snapped conrod?

just discovered I have a broken rod, there is no damage at all to piston, cylinder bore or valves. there is no strike mark on the piston crown. total mystery as to what caused problem. my problem now is getting a replacement rod as the bike is an import and a bit of a turkey. the engine is a nc23e and the bike is a nc31. does anyone know of any other rod which will fit. cheers for any info.