I guess it depends on how far you want to drill down on "original", but the majority of restored warbirds flying today are using their original type engines.
Sometimes the aircraft may be using a different dash # (or model) of the engine than when they left the factory due to parts availability, complexity, etc.. (No need for a two stage supercharger optimized for power at 24,000 ft when all of the current flights will take place below 10,000 ft.), but there are some aircraft that ARE using the exact same dash #/model engine as delivered.
Here are just a few examples.
F4U's are still using P&W R-2800's.
AT-6's still use the P&W R-1340-AN-1.
P-51's still use the Allison V-1710 or RR V-1650.
Most Sea Furies have been re-engined to use the R-2800, R-3350, R-4360 because off cost and parts availability of the original Centaurus engines.
The reproduction FW 190's use Russian/Chinese or American radials due to parts availability of the BMW 801. Currently this original FW 190 is using an original BMW engine.
FHCAM - Focke-Wulf Fw 190 A-5
Bf 109/Hispano Buchon rebuilds are using both RR and DB engines. Currently there are about a dozen DB 601/605 engines in running condition.