Well gearbox all back together again. Blind layshaft bearing replaced together with the mainshaft sleeve gear bearing and oil seal (bugger getting the circlip in with a new oil seal) and currently no leaks!
Kept the rear wheel sprocket at 42T and change the engine sprocket to 21T, std A10. Did change the close ratio box 1st gear to std A10 which has made it easy to pull away what ever the incline. However, 2nd gear remains very high and not very usable.
Will put a few more miles on the bike to let it all settle and for me to become more familiar with it all and then may change the rear wheel sprocket to 46T?