The engine may have been replaced with a 235. The captain bars are hard to see behind the starter and on the other side under the manifolds . The Canadian GMC 261 engines I have seen are green and have a stamped serial number starting with a W ------ on the flat surface behind the distributor.

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