IMO both skis are too much ski for your beginning level. At the speeds you are starting at you would do very well on a shaped ski such as an HO Triumph or an O'Brian Syncro. (we own both skis.) I have seen good skiers take both these skis through a course at 28 off 34 mph. So you will have a lot of room to improve before needing to upgrade your ski. Both are excellent open water ski's as well which is a real plus..(high end skis are rarely open water friendly).
65" would be good for your size however 67" will not be a problem until you move to the 22 off 32+ mph range and than you may find the 67" a little sluggish around the balls.
When choosing (or wanting
) a new ski, I refer back to a visit to Coble ski school and asking if it was time for me to consider upgrading my ski. I was told that water skiing is one of the few sports where the equipment (ski) needs to match the ability level of the skier.Buying a ski designed for skiing at levels you are far from mastering will do more harm than help to your performance. I kept my ski for another 3 years.
Good luck in your search.