Don't know about the Cessna with a Leyland motor, but there are currently two aircraft on the Australian register which have Leyland donks. VH-FGB is an Amateur replica ME109 & it has a Leyland V8 donk. VH-QQQ is an RV6, it has a Leyland P76 donk.
Used to own a Leyland P76 once, found it to be a much better vehicle than we were led to believe. And the boot capacity was amazing!!