I am new to the KTM kids bikes world and just acquired an 2006 KTM pro Senior, the motor is out of the bike due to the previous owner starting an cylinder and head swap. They put an 65 cylinder and head on an 50 lower end. Is this a common swap? Are the Gasket sets the same or do I need to order one each? Was told it was ready for the head gasket and re-installation, having mixed feelings about the condition of the motor but it looks extremely simplistic.