318-3 Closed Chamber Truck Heads

Gidday FABO'ers

Recently I found a pair of bare NOS 318-3 Truck Heads.
These use a different spark plug to normal LA heads and the only other mjor difference I can see is that there is a water jacket entry in between the intake ports (where the exhaust crossover would normally be).

I'm hoping to use these on my build, does anyone know any other differences or reason that I should not use them?

Pics below

Your experience and insights appreciated

Pete

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So, 70coupe, did you ever use those heads? I have a set that I may use on a 273 motor in a 66 Dart GT.