When I removed the first valve spring on my 305 to do a stem seal replacement job I discovered the spring had a broken damper inside. It looks like I will need new valve springs. My engine is a HO L69 305 with a Crane 2040 Powermax cam. Should I just stick with stock springs or go with either Comp 981 or Z28 springs? The old instructions with my cam recommends a spring upgrade with a rate of 432 lbs/in.