I've compiled a discography of Alberto Castillo with the orchestra of Emilio Balcarce on Spotify. These songs were recorded in 1943-1946 after Castillo split with Tanturi. Unfortunately not all of the songs were available on Spotify but you can have a look at the complete Castillo/Balcarce discography on www.tango.info.
To learn more about Emilio Balcarce I recommend reading the article about him on Todotango. Balcarce composed the amazing "La Bordona" and played with Pugliese as well as in Sexteto Tango. In 2000 he was appointed the head of Orquesta Escuela de Tango, which was featured on the amazing documentary "Si sos brujo".