No JOC or MCC required a Mustang is a CS23 aircraft and certified for single pilot ops and therefore does not require an MCC for the rating to be issued; even if you chose to operate it Multi Crew an MCC would not be mandatory for private ops. In-fact on private ops your "second pilot" would only be a "safety pilot" as multi crew time is only recognised on CS23 aircraft if you are under a multi crew ops AOC.
JOC is not an "actual recognised rating" and has no relevance to issue of further ratings. It seems to be something that ATOs now use to generate more revenue from under utilised sims.
An ME/IR is what is required to do the type rating so while the MEP does not need to current to start the rating, you generally need an MEP as the platform for doing the initial ME/IR.
An MCC is only needed for issue of a CS25 certified aircraft type rating.