None of commercial examples i know of is top-fermented. However my colleagues sometimes use California Common yeast strain (Wyeast California Lager, WLP San Francisco Lager) - with moderate success. The lower temperature the better, going as low as 57F. This beer is rather high gravity and warm fermentation will make alcohol notes too prominent in taste. Alternatively you may want to try some ale yeast that is able to ferment in such low temperatures, like German Ale or Scottish Ale from Wyeast.
(and btw., Zywiec Porter is here considered poorest of all produced in Poland)