Apologies for the thread-jack, but I have a very similar question.  I'm shooting an event (don't worry, the results aren't critical at all) tomorrow night, it's a parade lit only by streetlights.  I need ISO3200 to get 1/60 at f/2.8 (my fastest RZ lens), and I have 3 rolls of Delta 3200.  I shot a test roll tonight under the same lights that I can try one developer combo out on.
I have on hand some Rodinal and some D-76.  I want to use the latter 1+1 but most of the 
times listed on MDC are for stock, presumably for the purpose of dissolving the grain a little.  Can I deduce from the ISO6400 entry that one can just use double the time for half the dilution and therefore go for about 21 minutes for ISO3200 in D76 1+1?  That relationship doesn't really hold for other films, it's more like 1.75*time for 0.5*dilution.
I saw 
this which seems to say about 19 minutes once you apply time/temp conversion, so I guess that's not much of a difference, given variations in agitation technique.
Any suggestions?  Big grain is fine but it must be sharp, and I need 3200.  DD-X, Microphen and other fancy stuff is not available locally.