Hi Joe,
For a first cut at a PN for this boat why don't we go to the US Sailing rules? The base PN for the previous SC17 was 73. The major changes between this boat and the old boat are in the sails. The mainsail is larger and square top and the boat has a spinnaker. The adjustment factors are as follows: 0.95 for the larger mainsail
0.995 for the square top
0.96 for the spinnaker
The boat without spinaker is slightly lighter than the old 17 but add the pole and rigging and sail and sheets and blocks etc and we are back up to the old 17's weight. The boat is 6 inches wider out of 8ft, or 6%, which will be hard to find in boat performance but the rules say wider boat so we better apply it. That is another 0.995. This brings us to a total adjustment factor of 0.9029. Apply this to the original 73 PN and you have an estimated PN for the new boat of 65.9 calculated using US Sailing rules. Looks like a fair starting point to me.
Bill