On 11 July 1943 Bassoul was ordained priest and was appointed Chaplain of the Melkite Basilian Salvatorian Order.
In his short tenure as pastor he was instrumental in the planning for the construction of the "Annunciation Melkite Catholic Cathedral" in Roslindale.
After the consecration of a bishop in 1962, John Elya, BS, assumed the parish.
From 1962 to 1971 Bassoul headed the Melkite Greek Catholic Archeparchy of Homs.
Bassoul was co-consecrator of the Archbishop of Beirut and Byblos, Habib Bacha.