I had twin power electric fans on my supra, after some airflow testing I found that the stock fan/shroud still moved about 3 BPU's more of cooling power. Just a thought before trying for that .25 hp you might get from the electric fan. The way I did it was I bought an aftermarket thermostat and wired the fan to relay which was wired to the thermostat to control fan on/off and speed autatically based on the cars temp. Here is a general guide that I used when doing mine.
http://www.aaroncake.net/rx-7/efaninstall.htm