The 2-port head has a very dismal inlet tract, and I agree with Richard that there's nothing to be gained by fitting larger valves__certainly nothing you'd feel in the seat of your pants! If you're planning to keep the car/car's engine in original appearance, then you're just going to have to suck it up and take what you can get.
When I built the Longbridge engine for the car that Jim, aka healeyblue, restored, I fitted it with a BJ8 camshaft (and also a raft of polymer coatings, but more in the name of efficiency & longevity, than performance gains); you might ask him for his opinion on how it runs today, but I am not sure if they ever got the chance to drive it before the engine was removed and sent to me.
I did manage to get a few pics of the galley head before I put the core-plugs back in, to give you some idea of what the intake charge__air/fuel mixture__has to thread its way around to reach the cylinders. It's not pretty! If you're not concerned for originality, don't miss the last pic...
And for the kill shot! Looking forward from the rear:
Down the galley itself, and you see the row of head-studs that bisect the corridor.
Same shot, but from the front of the engine.
From the induction standpoint of a Healey, this is everything that the 2-port head is not