[Andrew Rowe]

Camshafts for the flatheadheads do come in different lengths.
I try and use a T5 cam (Truck ) on carrier engines, better torque curve. Your one is designed for the "Egg type dizzy" , so the only way to fit the "crab dizzy"
is to use the adapter plate. The previous post make sense also for the position of the slot, I have also seen a key adapter for the slot on the end of the cam, but I don't think this applies in your situation.