Glad to see you are considering an i-Pilot Mark. You are one of those fishermen that could really put an i-Pilot to good use.
I think my boat is lighter than yours (not sure). My i-Pilot is just the 12v .. 55 lb thrust Power Drive V2. Mine is equipped with the 54" shaft. Shaft wise, I wish it was a couple inches longer (don't we all?) because sometimes (rarely) in 1-foot waves, my prop will come up out of the water. But, as you know, the bow of my boat sticks WAY up in the air (typical Gregor). So a 54" shaft is probably plenty for your boat. Definitely don't go for the 45" shaft but a 60" shaft on your boat would be a waste and would unnecessarily take up more precious space.
As for voltage, like I say, mine is the single battery, 12v. model. When mack fishing, I have found that, near the end of a 6-hour day of fishing where we are using the i-Pilot heavily all day long, the battery gets a little week near the end of the day. That symptom would definitely not be an issue with a 2-battery 24v. system.
So, in summary, if I were installing an i-Pilot on your boat, I would go with the new
Power Drive V2 70. It has 70 lbs. thrust (a little more than my 55 which is better for your heaver boat). That
Power Drive V2 70 is a 24 v. system to better serve your heaver boat and it's more powerful 70 lb. thrust motor. And like I say, no need to get the 60" shaft ... for your boat, the 54" shaft would be plenty good.
The one drawback to getting the V2-70 is the cost and maintenance of two batteries instead of one and having to find a good location in the boat for the second battery.
I suspect that you already have an on-board charger. But if you don't, that is another toy
WELL worth considering.
One last thing Mark, if/when you get and i-Pilot and/or an on-board charger, come over to my place and take an up-close look at my installation before you begin. There are a couple things I have done that I really like and some things that should have been done differently.
Enjoy tricking out your ride Mark.