OK. We have tried the Merlin, Taurus, Dagger and Tiger. How about the Mercury? Peregrine power on 87 octane, reliable and in production. Wanted for Blenheims but this is becoming less important just as the Peregrine is being shut down. Lighter weight than the Peregrine and quite suitable for tropical service. Maybe the weight saved could go into increased armour for a GA role.
Essentially we are seeking a sound, available production engine in the 850 to 1,100 bhp class. Ideally air cooled to free up inner wing space for fuel.
Peregrine is going out of production.
Merlin is in too high a demand (we now know Petter was able to fit it.)
Taurus is otherwise wanted for Albacores and Beauforts.
Tiger is too unreliable.
Mercury can be available but at the end of it's development.
I have to go with the Dagger. Available, useable and with development potential.......