For drip irrigation, you need a pressure regulator and a fine mesh filter arrainged like this picture of an entire kit
http://www.sprinklerwarehouse.com/Xerigation-0-75-inch-Low-Flow-Control-Zone-Kit-p/xcz075prf.htm(value, filter, & regulator). You MIGHT be able to use the toro valve, but I'm not sure. Some valves will not properly operate (i.e. close) if the flow isn't high enough. I tried looking for some details on a toro 2604 valve but wasn't able to find the details on them to indicate at what water flow rates the valve is designed for.
The kit shown above (sold by the sponsor of this web site and available at irrigation whole-salers like Ewing) includes a valve that is specifically designed for the low flow of drip irrigation.
Now I've had no problem using a rainbird valve designed for flow rates from 0.2 to 20 gallons per minute that simply supplies water to a single rose bush (likely about 4gph, which equates to 0.06gpm) without problems. So your existing valve might work. But depending upon the flow rate you plan to use, it might not.