I am sure that we can sort you out with some gears to get you started. I assume you mean a close ratio box?
Are you going to race a 125 or 175? if you are racing a 175 then there is some advantage to using a D7 road gear output pair 26t sleeve gears/21t press on gears. You then use the 25t Mainshaft sliders/22t Layshaft sliders from a standard road box. The only thing that you need that's not standard is a 19t main shaft first gear and a 28t layshaft free spinning gear. I don't have the tools to make these up but there a plenty of people in the club that do. Have a look at the gearbox problems page in the tuning manual and Mikes gear box page on the site, there a big help.
If you want to put a post on the main forum outlining your plans and progress I am sure we will all be happy to help if we can