Spitfire Vb engines in 1944

[LukeFF]

There were a number of squadrons still operating the Spitfire Vb in southeastern England in the spring-summer 1944. What engine model would be most appropriate as the default choice for that time frame? We of course have both the Merlin 46 and 45 to choose from.

[Madov]

Likely the Merlin 50/50M and the 55/55M.

[ZachariasX]

Probably the Merlin 45 as it more closely mimics the 50M/55M prevalent in remaining frontline Spitfire V in that theater.