Won't it confuse things somewhat if this book follows on from where the original left off, because that's what the film (part II) does?

So it's either going to confuse things by following a different course or be predictable by following the same one?

"Neri, take a train to Rome. Light a candle for the Archbishop." - Vincenzo Corleone

"But if he betrays me your prayers will not be swift enough to catch him on his way to hell." - Salvatore Guiliano