I'd suggest it to replace the SMB3 Sand Blocks because they don't have masks. That would mean you can save the SMB3 Wood for custom blocks that require masks.
Before importing (which, mind you, is just hitting copy and paste 9 times in a row), you should probably change the colours a bit. If you're unsure about when the colour is right, look at the block you used as a template. It's mainly the brightest colour I'm concerned about. It should be brighter. Also, why did you swap the two texture colours?
After importing, changing colours becomes a few dozen times harder.
Anyone can recolour a graphic (or ask someone to do so); therefore it's the graphic designer's job to present a template with the best quality of colours and shading for the tileset. Flawed shading on said template just makes potential users of the graphic steer away and use something else.