Catalyzes the transfer of the 2-phospholactate moiety from (2S)-lactyl-2-diphospho-5'-guanosine to 7,8-didemethyl-8-hydroxy-5-deazariboflavin (FO) with the formation of oxidized coenzyme F420-0 and GMP. (2S)-lactyl-2-diphospho-5'-guanosine + 7,8-didemethyl-8-hydroxy-5-deazariboflavin = GMP + H(+) + oxidized coenzyme F420-0 Inhibited by EDTA in vitro. Optimum temperature is about 37 degrees Celsius. Thermostable. Still fully active after heating at 80 degrees Celsius for 24 hours. Activity begins to decrease after heating at 98 degrees Celsius for 30 minutes. Inactive after heating at 110 degrees Celsius for 30 minutes. Cofactor biosynthesis; coenzyme F420 biosynthesis. Homodimer. Belongs to the CofD family.