What is the College of Rice's highest overall for the guard position?
CREATE TABLE "atlanta_falcons_draft_history" (
  "round" real,
  "pick_num" real,
  "overall" real,
  "name" text,
  "position" text,
  "college" text
);
SELECT MAX("overall") FROM "atlanta_falcons_draft_history" WHERE "position"='guard' AND "college"='rice';