Believe the Cheyenne I & II are fitted with the PT6A-27, same as the DHC6 and BE99, altho possibly the PT6A-20. However, uprated engines may have also been fitted by STC.
Either engine is more or less bullet-proof.
FCU and propeller governor rigging is very important, and is best left to those that know how.
Make sure the ships battery is well charged for starting, and follow the AFM with regard to charging between engine starts.
These engines, altho of an old design work good, and last a long time.