Not quite... fort has different rules patched in. Fort I think reduces converts by 50-75% instantly (doesn't seem to matter whether bonus fades in). Before the patch, fort converts were as good as any other, and I don't think anything has changed.
GS, Orc bonus, and so on do not have any effect.
I haven't played a race with spec converts in like forever so someone who uses that more might have better information.