If you want finer grain than Delta 100 and want to maintain a long tonal scale you really have only two options - Fuji Acros and TMax 100, either one developed in XTOL (various dilutions). TMax 100 is slightly finer grained than Fuji Acros (they are both exceedingly fine grained), and has similar tonality to Delta 100 but with a slightly more gradual shoulder. Acros will look similar in the low and mid tones but has very high highlight contrast. I'm not saying that's good or bad, just a characteristic to be aware of. Personally I'd suggest TMax 100.
By the way are you from Montreal?