How would this microphone be for recording spoken voice into a hard drive using Sound Forge software (through a preamp) for the purpose of producing educational CDs?
It depends upon the quality you are seeking. Will the 512 work? Yes (assuming the use of a preamp).
Will the 512 sound as full and rich as the SM7B or a KSM44? No.
Sound is subjective. We cannot predict if the 512 will provide the sound quality you desire.