Bulk updating of Start/Due dates on features Merged

When estimating in story points, I only know which sprint a set of feature are due in, not the 'total days' on which they will be worked. It would be great if I could set due/start dates via the bulk update feature. Currently doing it manually and it makes the roadmap gant very neat and gets the client team into the head space of 'ok so my feature is in that window' rather than 'ah, 3 days - my feature is due Wednesday!'