Valve springs are confusing me

Is this the cam you are using? If so they recommend a Crane spring, although a fresh stock spring may work with that cam also?

Cam...

http://www.summitracing.com/parts/SUM-K6400/SuggestedParts/?prefilter=1

Spring...

http://www.summitracing.com/parts/CRN-99839-16/