@burstminergrow If it was me...
8TB x 125 (not SMR drives)
2 x 16 Port SATA controllers per PC ( 32 Drives per PC)
using 4 PCs x 32 = 128 Drives
or
2 x 24 Port SATA controllers per PC ( 48 Drives per PC)
using 3 PCs x 48 = 144 Drives
Its usually cheaper to buy the USB 3.0 drives then extract the drive from them for use with a SATA/SAS controller. ( Warning will void your warranty)
My advice would be to start small then grow as there is a learning curve to Burst. Also your newer GPU's will be best for plotting. The use the old GPU's to mine.
Good luck with your build.