Olly:

That would be Balboa Street, not Bilboa. The streets
that run parallell are Anza on the north and Cabrillo
on the south. It is 3 blocks north of Golden Gate Park.
Depending on the actual street, it is about 2 miles from
Ocean Beach.

20th and Balboa would be in the Richmond District of San Francisco and was at the time predominantly composed of
Irish and German families. There were a sprinkling of other
ethnicities as well. If Catholic, I believe his parish to be
St. Monica's. If not, it would be Star of the Sea. St. Thomas
Apostle did not exist in the 20s and 30s, but is at 39th
and 40th Avenue at Balboa Street.

You may also want to be in touch with the Plasterer's Union
to see if he was a member.

You may also try MacAvoy O'Hara funeral homes on Geary Street (about 9th Avenue, if I recall). They were a popular funeral home among the Irish and "in the neighborhood" so
to speak. Also -- St. Mary's Hospital on Stanyan Street
was and is a Catholic Hospital, and one he may have chosen
to use.