For 100W RMS into 8Ω ,you need at least +/- 44V rails for an equivalent Vdc (rms) of 28.5V. with +\- 4V drop minimum for output stage saturation avoidance to deliver 40Vp sine.
With Irms of 28.5V/8Ω = 3.6A (rms) and a Ip= 40V/8= 5 Ap
The unregulated PSU with 44Vdc/5A= 4.4V ripple or 10% means it will saturate ,,so you now need 46.4Vdc min.
so why not get a pair of 48V cheap PSU, with <0.1% ripple?
Otherwise unregulated PSU needs RC=5T to get 10% ripple and 10T to get 5% ripple.
Thus for R=8 Ω and with 50Hz, T= 10ms then for 5T or 10% ripple you need, C= 5T/8Ω=>6.25 millifarad caps rated at >=70V for no load rise of 140%. But 10r ripple results in lots of distortion, so this is poor quality. Also the ESR must be <= 50 mΩ.
When I made a 150W amp at age 18 , I used 100mF (100k μF) pair of high grade caps with ESR ~ 10 mΩ. These were cheap at the time, since they were used in mainframes.
I doubt your Amp will deliver 100W rms unless you offer more details. THe Nakamichi design does not use full negative feedback from output to input, which results in low phase shift and low THD, low IMD in treble range,mwhich also gives good 2D imaging of source on stage.
So It depends on your requirements for quality.