Hey, I'm here again))

I got camshaft COMP Cams kit 12-305-2 [49]
12-305-2 - PURE Energy
for my Chevy Van 1979 with 350cid, carb, stock engine.

Due to I need to replace my old valves, so please tell me, what Overall Valve Length should I buy? Because it's not stock camshaft at all, and I'm not sure about stock (4.911 in.) valve length.