Ian: I tried T-Max a l-o-n-g time ago and hated the results (muddy and blocked simultaneously) but I never really experimented with it because it was so bad. I'll try sanking's formula. That's with T-Max 100? I'll be shooting 4x10.
Photo Engineer: I don't care about speed... only acutance and grain... in that order.
If you are serious about this, I suggest you use ISO 12 with an ISO 25 film and develop accordingly.