The angle strips are sold by length or buy some angle and paint. How are you going to attach angle strips to the bed sides? The angles are sold punched or not punched. Seems like you want punched. Then drill holes for side mounting and drill wood to match punched square holes. I think the only difference in 55-59 and 60-66 are the holes but that may not matter depending on what you have that is already drilled or not.

Right is right, even if everyone is against it, and wrong is wrong, even if everyone is for it. - William Penn