When the clutch is installed as the manual shows, the force applied to the clutch wedges the shoes harder against the clutch drum. The first and second clutches are installed in opposite directions, since the first speed clutch is turned by the crankshaft, and the second speed clutch is driven by the clutch drum through the first speed clutch.
You could increase the RPM at which the clutch shoes engage by lightening them, using a stronger spring, or by moving them closer to the center.
Beware though, when the second clutch grabs, something has to give. A higher shift point means more momentum, and more force that will need to be absorbed somewhere. The dampening pucks do this, but if they are hardened from sitting there for 30years, or if you have a higher RPM shift, and more torque from a kit... your second gear may loose a few teeth.
Maybe slipping the clutch a little is a good way to absorb the shock.
I'm not really sure what the answer is here, since this is all theory to me.
If anyone knows what works , and what doesn't regarding these engines, it's Paz.
I'd like to know also, since I don't want to go to all the effort to build an engine this winter, just to blend the transmission the first time I run it next spring. Then I'll probably go back to the E50. Yuck. :P