You'd really be pushing the limits of the technology to try to drive the signal >100 km. Not only do you have the straight out power loss due to the distance, you also have other factors such as dispersion that makes recovering the signal reliably more difficult.
If simple amplification was all it took, it would be an easy fix. Amplification doesn't fix a phase-shifted or noisy signal though. Unfortunately there's no way to tell exactly until you actually plug it in and validate the link's transmission characteristics.
Generally folks are better getting an Ethernet service vs. dark fiber. In such a service, the carrier is usually multiplexing and carrying the signal through multiple active nodes that actually perform an optical-electrical-optical regeneration.
