your peak output voltage will be about 28V.
this limits your power to about 50W into 8r, about 90W into 4r and about 130W into 2r. I have assumed a 300VA transformer driving both channels at the same time.
All these speakers can be of the severe rating (60degree phase angle) since the low voltage rails do not stress the output transistors.
Since it performs so well into 2r you could consider bridging if you need more power;- 180W into 8r at 60degree phase angle. The 300VA and two PCBs now form a single channel amp. It would be cheaper to buy a higher voltage transformer for more power.
Leach version 4.5 needs in excess of 40 volts to perform at its best - that is the reference voltage for the input stage cascode. Earlier versions did not use these zeners, and may perform well on lower rails. IIRC, Dr. Leach recommends >45V minimum.