When I first read and replied to this thread, I did not understand the full context of the conversation, or what a ‘SuperRok’ conversion actually entailed. Now that I do, I can say that while it’s probably worth having the lighter spring for the power valve, this really is apart from the main considerations that the conversion should be focused on (e.g., advancing the timing, getting the carburetor adjusted for the new configuration).
I recommend anyone tracking the subject of SuperRok conversion to head to this thread which covers it in greater detail.