I was accepted into the Catholic faith 10 years ago at the age of 58. I was raised Southern Baptist and like Billy Graham I was born and raised in NC. I saw him many times as a child and young adult. I went to many of his crusades and yes I answered the altar call many times. I became Catholic after many years of studying the gospel and the history of the Christianity. In the end I converted for one reason and one reason only. Its the truth.
You say you "answered the altar call many times" which tells me you probably didn't understand what saving faith did in your life and you thought something was lacking which is why you eventually converted to Catholicism. Did you give up your assurance of salvation when you did that?
Graham's ministry was preaching the gospel to everyone he could. What each person does with that knowledge is between them and God. He believed, and I agree, that the Holy Spirit is who gives the increase of faith once the seed is planted and watered.