I am cheap and cannot afford that much for a gearbox. As for ratios, a CR is nice for racing but as John H. pointed out the races are so short that acceleration to the first corner is more important. My ratios cover the same range as standard.
From Nova's picture they kept the ball bearing high gear with sleeve bearings. I am making mine like the Quaife with roller bearing and needles on the mainshaft. It uses the Triumph sprockets. Back cut dogs and the rest.
There are three tracks, look again (three forks so there must be three tracks). The same setup could probably be used on the stock gearbox but I doubt many people would want to pay for it. An "up for first" drum could easily be made.
The starter for the A65 is on hold at the moment. Too many projects with too little time.