These are way-old machines. The last MacOS driver for the 1050e was released in November 2014, for MacOS 10.10. The last MacOS driver for the IC-303 (the Fiery for the C6500) was released in March 2015, for MacOS 10.10. (Assuming your C6500 has a Fiery controller.) The CWS workaround in the post above sounds good for the latter. For the former, maybe you can use PageScope utilities, like PageScope Direct Print.