Aug. 29—NORMAN — Spencer Rattler has never shied away from dreaming big. “I’ve been setting goals since I can remember,” the OU quarterback said. “I just got off the phone with my quarterback coach a while ago. ... We’ve been talking about national championships, Heismans, since I was 8 years old. To be pretty close to it, and going for that goal, is something we’ve got to check off the box. “I…