Ed_Moorman- result of 3/4 loop is straight down. 5/8 loop is what you meant for Cuban 8 entry?

Just think of it as an Immelman with a little more loop action. In fact if it makes you nervous to do rolls while in inverted dive, just slowly transition from the Immelman by adding a little more loop each time until you are comfortable. Remember that altitude is your friend when learning new maneuvers.