With the fan belt pulley at its shortest position I measured the length of the fan belt in a 1917 Cdn Touring with a string. The length was 27 3/4". When I try to find this length of belt the closest that comes up is a black 28" grooved, there are no grooves in the bottom pulley ....would this type belt work well?
I don't believe you need the micro groove. No real advantage to them that I can see. I'd give this one a try. http://www.modeltford.com/item/3964-28-3/4END.aspx They function well and the belt only needs to be snug enough to turn the fan. In fact, you should be able to turn the fan with the engine off. If you can't, the belt is too tight.
You can spend more and get a leather belt if you have a show car, or a heavy duty, but the one John posted is least expensive and will probably outlast the owners of most T's.
The 28 3/4" belt mentioned should fit fine ...mid adjustment point.
A poly V belt will outlast you.......and maybe the car.......