I have a Fuji 43cc EI in a Willhobby FW190 with 72" wingspan. It flies great with this motor combo. Was a real dog with Fuji 32cc in it before that.
Just remember to use big motor in radial cowled planes and you will not have a problem hiding it in the cowl.
Great choices will be Zero, corsair, FW, etc.
By the way, I'm glad you found an SPE 43cc that runs well. Mine was a dog compared to the Fuji 43cc, could not even give it away to any club members.