I ran a flex lite elec fan on a switch with underdrive pullies on my 92 GT. The only time I had to turn on the fan was at a red light i never had to turn it on on the hwy. I put mine on a switch so I could run the fan on between passes at the track.
Right now I've got a Flex-a-lite electric fan wired up into the battery (yeah I know nto the best thing to do, I'll switch it soon), underdrive pullies on the crank and waterpump, and stock alternator, the battery is a Yellow top Optima. So can it be done? Yes. Is it best to wait till you get the new alternator? Yes. I haven't had any charging problems...yet. But its been running like that for about 5 months now. Car starts fine all the time. No problems either at night with A/C, stereo, fan, and lights on. The voltmeter is almost all the way down but hasn't died...yet. I will be installing a 3G 130amp PA alternator soon though, got some subs and amps going in so yeah definately need it now.
I ran my electric fan on the stock alt with UD pulles for a bit before I upgraded to a 3G. To my benefit I also was using an optima battery, DC controler(probably the only thing that kept my motor alive) and was already planning on a 3G in the near future. At a stop my lights would dim a lot. I suggest sticking with the mechanical fan if you don't want the 3G. You can plan on spending 200 bucks or so from www.paperformance.com for a 130a 3G not including the wireing which can add up pretty quick for the correct gauge wires, fuse/fuseholder and connectors. If you are going to go electric do it right. Taurus/Mark VIII, dual spal... any number of proven fans and a DC controler. I don't have any experience with proform but the general thought is they aren't so good along with the black magic even for a stock motor.
Kevin
i ran a small elec fan with a stock alt. i did have UD pulleys but swapped out the ud alt pulley for the stock one. swap back to the stock alt pulley and see what happens.
the difference b/w a stock alt pulley and an UD one is next to nothing. maybe .5 HP 99% of the UD gains are mostly in the crank and water pump.
I just installed an overdrive alternator pulley on my car the other day, it is MUCH smaller than the stock pulley. It is 1 7/8" in diamater and I had to turn down a 1" socket on a lathe at work to install it.