the advice to use stock gen 3 cams in a gen2 head, is not 100% sound. these later cams have different acceleration profile and need the larger diameter bucket if they are to be long-lasting. Therefore, such a change needs to go with gen 3 shim under or shimless buckets
the main reason to install longer duration/higher lift cams is to move the torque point upwards which means higher revs are needed to amke the extra power. rarely, if ever, do factory springs work with modified cams. You should always buy a spring suited to the cams