"They" (Intermatic) also recommend that the transformer be loaded to at least 50% of its rating, or an overvoltage condition will result.

You might try a 121 watt xfrmr.
http://www.amazon.com/Intermatic-ML121RT-Malibu-Voltage-121-Watt/dp/B0002YTPL4

Intermatic also manufactures an 88 watt transformer if you think it's more suited to your needs
http://www.amazon.com/Malibu-ML88T-88-Watt-Ground-Shield/dp/B0000DG57B/ref=pd_cp_hi_2
.