None of us will ever know...some of us will Google and come up with Porter.
My take , and so will others vary but I remember as a little boy my dad, telling me Piet Du Toit (a relatively small in stature tight head that played for Boks and Boland in fifties/sixties. He could lift an Afrikaaner ox by placing himself underneath and grabbing the 2 front legs...
We really don't know but can have our guesses, ie Ray Mordt , probably the strongest backline player, not a big man but immensensly powerful and one of the hardest to bring down.
Maybe, it could be interesting to hear views from others. It does not mean the heaviest.
