Here is a picture of a bellhousing from a 1957 235 motor. Notice that the corners are sloped.
1957 235 bellhousing

Here is a picture of the mounts on the motor in my truck.

1953 Passenger 235 PG motor

My truck is a 1951. I don't know what was used when my motor was replaced. My bellhousing does have the holes on top for the floor starter linkage. I am keeping the current belhousing for use on the 1957 motor that I am having built.

Todd