Tell me the lowest Grid for engine and driver of emerson fittipaldi with more laps than 70
CREATE TABLE "classification" (
  "driver" text,
  "constructor" text,
  "laps" real,
  "time_retired" text,
  "grid" real
);
SELECT MIN("grid") FROM "classification" WHERE "time_retired"='engine' AND "driver"='emerson fittipaldi' AND "laps">70;