During round 8 when the Position being picked was rb, what was the highest overall pick?
CREATE TABLE "washington_redskins_draft_history" (
  "round" real,
  "pick" real,
  "overall" real,
  "name" text,
  "position" text,
  "college" text
);
SELECT MAX("overall") FROM "washington_redskins_draft_history" WHERE "position"='rb' AND "round"=8;