Nice looking kit DJP! From personal experience, you can't go past a natural stain on the Spalted tops, but then some of the coloured ones I've seen here look magical too.
I did not grain fill, or even use timbermate on mine, and if you wanted to get an idea of how it would look with a Dingo Tone clear coat on it, I used a damp cloth over the face, and it sealed the deal for me. Don't over do it, and perhaps someone could suggest a better product to use instead of water since it did raise the grain slightly when I did it.
Remember that these tops are extremely thin(around 0.5mm thick) so take it very easy on the sanding.
Good luck with it, and keep posting up your pics as you progress!