Fiberspar's guide doesn't mention the R6000, but given their other suggestions for this sail, I suspect that it's not the ideal mast for your sail... On the other hand, mast compatibility is also a matter of preference - there are no absolutes. A heavier sailor will usually appreciate a stiffer, higher-carbon content mast with a faster response than a lighter sailor.
http://showvantage.com/fiberspar/msguide/99_00/
north_sails/iq90.html
Looking at the Warp recommendations, the R6000 still isn't recommended.
I would certainly give the mast a try. If it feels good and performance is not critical, use it. If performance is critical, try to find the right North mast and compare how the sail feels with each mast.
Given the age of the sail, I suspect that keeping a tight budget is more important than every last bit of performance: it will probably be just fine for you.
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