Biermann - It's possible your block casting number might have been misread. It could be 3739365, which from my US reference resource indicates a 1960-63 Truck 261. It could be your Canadian 261 used the same casting number as the US truck engine, but I can't find anything confirming that. I think a 1958-62 235/261 oil pan may be what you need as they where the same block design and mounting bolt count.
Perhaps you can post an overall picture of the oil pan mounting surface, plus try and find the block casting date codes/marks tobetter ID your engine?
