If you watch Pumping Iron, you see Lou taking a number of amino acids and vitamins.
And consider that the majority of protein back in the day was Soy Protein. The only good tasting protein was the Reo Blair Milk & Egg Protein however it was super expensive.
I only carry Milk & Egg Protein when it comes to protein powder and thats it. You don't need 600 grams of protein a day.....