Cold Case w/ electric fan vs factory fan and shroud

Yep! First thing is that you need to determine why a 26" radiator is not cooling that 318. That should be plenty. If it turns out to be a overtired clogged up radiator, then you pretty safely look to a new radiator to solve the problem. But if the radiator doesn't have tubes cut out and/or signs of being clogged, you have to look elsewhere first.

That being said, you are correct in your observation about electric vs mechanical being about the same price if you include the shroud. What most people don't know is that the cooling aspects of both are also a wash in most situations. While I'd love to have you choose a Cold Case kit, that may not be necessarily the best solution for your needs.
Since cost and function are equal, it really narrows it down to just a few other factors.
1. original look and style vs hi tech look and style.
2. electric will free up a several HP because no drag on the belt to spin the fan. That in turn also lowers the temps a bit more.
3. If there is plans for a pulley system down the road, you will NEED an electric fan setup.
4. Sound! Electric fans make a unique sound. Some like it, some don't! So keep that in mind.

That's pretty much it!