You are on the right track, I'm not familiar with a Kennedy hull but at 16' I assume it's a relatively heavy boat. You need all the push you can get so 2 wide blades for sure. 74" is a good move if you truly have the room, but if it's an open hull you need to be careful of dropping the blade tip too far below the transom.
Sensenich JW and Whirlwind Whispertip are pretty much the same, they perform very similar to each other, have similar features (are actually interchangeable) and are priced the same. Both like to spin (2,800) which matches the SV540 power band well. If your primary goal is maximum thrust to plane out the large boat quickly for running in wet to deep water while also performing great running ground then either of these props will work great for you and you should base your decision on dealer, convenience, price specials etc.. Quality and performance is similar.
The Sensenich NGQ is a more expensive option (+$500 I believe), these blades are heavier with a larger diameter shank (stronger) and use a different hub than the 2 above (are not interchangeable). I run this prop on my SV540 and love it for running ground. These blades push well over a wide RPM range, I find that Thrust is very linear and controllable between 2000-2800 RPM which allows me to run slow and steady on ground.
If running hard ground is your primary objective, then you should consider the NGQ. Otherwise the JW or Whispertip would be my pick based on the power band tuned a bit higher and lower weight, both of which will give you better snap, which you really need to plane and control a larger boat.
