Hi Mike,
More important to choose the correct type, best is BCF but illegal now except for certain things, so that leaves AFFF, Aqueous Film Forming Foam as the best, cheap enough work well on all things car related.
Are the fans still going ok, got some metal in so can knock you up a rear strut brace at same time as doing pump rewire if you want, metal only about £3-£4, take 10 mins!!
tabetha