Looking for helicopter audio – MI-4 engine

A Finnish team of aviation historicians and enthusiasts is putting up a
display of the Soviet built MI-4 helicopter for an aviation museum display.

They have a short movie, shot in the 1970s by a MI-4 pilot, which will
be used. The black/white film doesn't have audio though.

The team is looking for engine sound for the MI-4 helicopter and has
asked help. If anyone happens to have video or audio recording of MI-4
chopper or knows where to get its engine sound please help.