Rear wheel spacing/ cog position? measurement please

Thanks everyone. I know what Im doing now.

I liked the sound of the fixed MTB by the way.

Its not really a fixed MTB though as it now has 700c wheels on it, it just still has an mtb frame. tires are 28c so on my none commuting rides I do a lot of gravel path stuff (farm tracks, converted railway lines etc, nothing hardcore I have another bike for that). info on the bike herehttp://www.lfgss.com/conversations/263535/#comment12139811 Ive just about got everything to do the frame swap now, need to add decals and lacquer first then time to build.