Dual valve springs stock on 2.02 915 J Heads?

If you have not bought anything i would recommend a custom cam.
Call comp or what ever cam manufacturer you want and tell them about your eng and the elevation that you live at.
They will recommend the cam spring and retainer(if need) to make a much better runner eng, than trying to pick a off the shelf cam.

You really will be Time and Money ahead. Most "off the shelf" cams are designed with near sea level performance.
I had Brian IMM with comp, spec out my cam(live at 6600 feet) I have been way happy with my setup!!!!