CREATE TABLE table_58271 ("Home team" TEXT, "Home team score" TEXT, "Away team" TEXT, "Away team score" TEXT, "Venue" TEXT, "Crowd" FLOAT, "Date" TEXT)

Tell me the away team score for 27 april 1974 and veue of mcg
SELECT "Away team score" FROM table_58271 WHERE "Date" = '27 april 1974' AND "Venue" = 'mcg'
SELECT "Away team score" FROM "table_58271" WHERE "Date" = '27 april 1974' AND "Venue" = 'mcg'