It looks fantastic, but I hope I won't sound rude by posting a few touch-ups and suggestions:
For the title, I went in and redrew it a bit and touched up the palette to look a bit more on-model and to be a bit smoother:
This one mostly uses the prior palette, but with a more natural skin tone and slightly different overalls (I know the sprite has the more indigo ones, so you can ignore that if you wish to use this in the first place).
I also made a slightly different version with fewer unique colors, but the goal of this one was to smooth the image further with more "in-between" shades to simulate anti-aliasing:
This version also has a little bit of extra shading for more depth. The gloves use the skin tone for shading here, and the boots and buttons use skin-ton colors to save on colors used.
Here are the images themselves:
The other thing is that for the sunset beach, I feel the ground shading should be reversed, like this:
This was quick and dirty, but I think that having a more saturated, red-hued palette like this with higher contrast and shading towards the top would accentuate the sunset because as it is it looks like the ground is being lit from below. I understand the sun is very low, but as-is, the ground looks weird with the sprites. That is just how I feel about it, though.
The hack in general looks incredible, and I can't wait to try it out!
[EDIT - A few more touch-ups]