I have managed to get it on chaps. By building the clutch one piece at a time, i have usually managed to get them on with the clutch built up, (except the plates). i now seem to have an alignment problem, the drive sprocket teeth are 1/8 of an inch in front of the clutch basket teeth, Is there an alternative width drive sprocket?
Hornets or ET models are different but not for the reason your wanting. The best solution would be to machine 0.125" off the oil seal sleeve. Its more common that the drive sprocket needs shimming to bring the alignment correct with the clutch but possible some that some aftermarket parts are not made correctly. You would also have been best assembling the clutch basket to the main shaft and the drive sprocket to the crank, tighten the nuts so everything sits flush and use a straight edge agains the outer row of teeth to find the true offset.