Obviously the good people at Spondoolies would be the best bet to get matching original hardware, but I have no doubts there are others who could make that connection for you.
If you're willing to pay for it then you can buy all their PSUs off the shelf from [specialist] retailers. Exact model numbers are in their respective guides, although I'm unsure if the two variants of SP31 PSU are the same as the two variants in SP30s. SP35 had no variant but a different 1600W.
Be warned though, they are crazy expensive due to their compact package, and part of the reason SP3Xs were such good value /expensive for ST to manufacture. When they are / were no longer viable for mining, you had $400-$600 worth of PSUs to resell.
Did you link the specialist retailers for our good man here quakefiend? Maybe I missed it?