So, if you don't mind a suggestion out of the blue, I think it would be very easy to improve this Kickstarter campaign.
So you have a massive NWN mod, and want to raise money to port it to Unity? Why not release the NWN mod then? Or, let's say, just the first 25% of the mod (which can become the demo version sometime in the future)? Some people still have NWN around, and a lot of people are familiar with installing NWN mods... Not to mention that a lot of your potential customers are from that scene. And since you're selling your game based on the story etc., people who like the start of the story will be anxious to see the rest of it and are more likely to contribute.
Then people can't tell you you're just talking and have no proof - everybody who wants to see what the project is about and evaluate the potential can download the preview mod and that's that. Then you make clear that the money will go into porting the content from NWN to Unity, and everything is clear. Somebody doesn't want to install NWN to check it out? Then they have no right to complain.
And yes, I can see how close association with an old engine might put some people off, but if you make your Kickstarter clear that the money is for porting the content to a newer engine, that shouldn't be a problem.