Suprol - Reversal processing
Nick, there is or rather was a very informative technical data sheet for May & Baker Suprol. May & Baker became Champion.
The data sheet was published in the 1970's and gave a lot of extremely useful and detailed information on a wide range of uses for Suprol, and this included reversal processing and adjustments to obtain different gammas etc.
Other uses were as a fine grain developer for commercial processing, and at about 1+29 or higher dilution for tank development, and it did give very fine grained negative.
Suprol is fairly similar, effectively equivalent, to Ifords PQ Universal and so would give you pointers for adjusting and using a developer like ID-62, or even ID-72
My copy of the datasheet is in storage but if you can't find a copy I'll try and dig it out next time I'm in the UK.