The BBMF have been known, in the past, to take parts from recovered aircraft wrecks, gate guardians etc. When the Shackleton was retired, some Griffon engines were then made available and converted back from the contra-prop configuration for use in the (then) two Mk19 Spits. The present day situation vis a vis Merlin engines for example, seems better than it was in the 1980s. At one time, one of the 'Flights Hurricanes used a Merlin 66 IIRC, with a four bladed prop. The props, by the way are, or were, from Hoffman in Germany !
To see the day to day life of the BBMF is incredible - the ground crew put in very long hours, and are extremely dedicated.