Comp 901s are similar to the Lunatis duals, but not strong enough for any profile larger than the XE268 they sell. They are a basic performance spring, nothing fancy or stiff.
On the J heads... You will need double springs for the cam that 416 should be getting (something larger than 245°@.050, which is very mild for a 4" arm). So have the spring seats cut and the guides reduced in size for them. Then get the springs the cam manufacturer says to.
Well, art is art, isn't it? Still, on the other hand, water is water! And east is east and west is west and if you take cranberries and stew them like applesauce they taste much more like prunes than rhubarb does. Now, uh... Now you tell me what you know.
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