Harvey Crane still does some oddball/ specialty cam regrinding; might try him. I think he is in his 90s now.
Don't go too crazy without evaluating the oiling system on this thing; along with the con rods and the hardware that holds the con rods together.
Im not sure about the valvetrain, but if its not adjustable, you can't do too much to the cam either. Best thing you can do to increase performance is more compression and or rear gear change.