Try 1:23
Seriously.
Not long ago I came across an old Shutterbug story about DIY sensitometry. There were a couple of small shots of a house using different developers. One was 1:23 in Dektol. I swear, it had the best tonality of the bunch, whatever could be gleaned off of that old newsprint. No mention of development times, nor how they came up with 1:23.
It will never be fine grain, of course, cuz that 80 grams of sulfite is spread mighty thin. Probably very high acutence.