There were actually several examples of the country being called Republic of Kenya in 1963. These were what...lucky guesses?
OK, I missed the part where you name any instance of this happening outside of the famous newspaper called the NEVADA PALLADIUM TIMES.
I won't hold my breath, but let me you ask you a few questions.
Who was the head of the state of Kenya from Dec 12th, 1963? Answer, it was the Queen of England. Does that sound like a republic to you? The constitution of 1963 says the Queen of England nominates the Commander in Chief and governor general, and that her majesty is part of parliament.
Who was their president on Dec 12th, 1963? They did not have one. The office of president was created when they became a republic, a year later on dec 12th 1964.
Why did Kenya release a 5 stamp set exactly on Dec 12th 1964 with REPUBLIC OF KENYA on it, announcing their newly becoming a republic, and never have any stamps before that date with Republic of Kenya on it?
If Kenya was known as the "Republic of Kenya" from 1963, why did their own constitution not refer to the country in this way, anywhere in the document?