My +4 had kingpin play from new. Went back to Morgan under guarantee who stated the play was fine.
First MOT issued with advisory 'kingpin play'.

Changed the kingpins with chrome when I fitted the Suplex kit. Did not change bushes as they measured okay.
Still a small amount of play one side.
My local garage does classic cars so has no problem with small amount of movement. As he says "It isn't as if it will fall off"