I was also worried about this, and am looking at the crane cams sold at SDPC one of the sponsors. They told me the 220/224 551/551 114LSA cam with Ls6 springs will last as long as LS6 cam and springs. I called crane and they said to check them at 50k to make sure they are working properly. This cam has very easy ramp rates so it makes since the springs will last long. Also the cam is cheap at 308 bucks

 

I was also looking at that one. I might have to give them a call as well.