Hi John,
All the old side valve Chrysler/Dodge/ Plymouth/ Desoto engines had a water distribution tube fitted to the block. It was intended to cool the valve seats to prevent valves from over heating and burning out, particularly at the rear of the block. I have replaced heaps of them in the past, BUT, have also found heaps of them missing, without any apparent problems, including on concrete agitators.
In saying that, Cranky's fix would be a good idea to make sure.
Cheers, Steve.