Firefly did some combat in Borneo towards the end of the war, even shot down a plane or two, on the combat capable side it its like flying a BF110C, while you have four hispanos, you have nothing else, no top speed, climb rate etc only Dive.
It did some ground attack, thats about it - by the time they arrived in the PTA the war was pretty much over, think it few a few strikes into Japan, thats it.
Fulmar would be a decent Early war carrier plane, however it had bunch of 303s, very slow - and was not a dedicated fighter.
What you would get is a new plane, but nobody will give it up for a Seafire.