The connectors should be available at most local parts suppliers. NAPA sells a 5/8 inch heater hose connector number NOE 6601737 for under $10.00

1954 Chevy 1300 engine 235 (1959)
1955 (first series) Chevy 3100 engine 261 (1957)
1927 (other brand) Model T- engine 327 (1968)