Part III of the Zen Variations is posted on PassDIY.com

ok, i studyed part 3. My transformators give only 42 V or 84 V. Is it better to drive the circuit with 35 / (42) V, to use something like 64 / (84) V like in boZ, or use a 2N3055 , R24 = 600r, to waste only about 2V in the regulator and not 7 like in Figure 4, and drive 40/ (42) V ???

Whats the consequence of using only 34 / (42) V instead of 40 / (47) like specified?

And if driving at about 64V i must decrease BIAS because at 80W each MOSFET they will burn. Is f. e. 80V at 1 A equvalent to 40V at 2 A, or should current be as high as possible for quality and voltage does´nt matter ?
 
If you feel that it's likely that your incoming AC will vary enough for the regulator to drop out, go for higher voltage on the transformer. Under 'normal' circumstances the regulator will dissipate more heat, but you'll be covered for when the AC line voltage drops. Around here the voltage stays within 1 or 2 percent, but other people felt that their line voltage was much more variable.
There was a fair amount of discussion on this last fall, go back and look for the thread.

Grey