Proportional reducer kit from photo formulary (Reducer III):
http://www.photoformulary.com/Deskt...tabindex=2&categoryid=38&selection=0&langId=0
They use the original Deck (Gevaert GR-3) reducer formula:
http://www.photoformulary.com/uploads/05-0030.pdf
Kodak studied it and tweaked it to the following mixture, Reducer R-5:
Stock A
Water 1.0L
Potassium permanganate 0.3g
Sulfuric acide 10% sol. 16.0ml
Stock B
Water 3.0L
Ammonium persulfate 90.0g
It is said that "Various proportions of permanganate and persulfate were tried to secure the most effective combination in the presence of the acid. This modified version of Deck's reducer with additional persulfate is now Kodak acid permanganate-persulfate reducer R-5"
(Grant Haist, "Modern photographic processing," volume 2, p. 65-66)
1 parts A + 3 parts B. Reduction starts right away so you should be able to eyeball it. Afterbath of a 1% solution of potassium bisulfite for 5mins is recommended. Haist says it's pretty much the most reliable and stable proportional reducer.
The Formulary product works exactly the same way, A+B working solution, then C afterbath.
Let me know if you try the Photo Formulary product, because I have a few overdeveloped negatives that I would like to try, and I had my eyes on a permanganate-persulfate solution.