The calculated distance (air line) between Gonbad-e Kāvūs and Qūchān is approximately 184 miles respectively 297 kilometers.
By car or train, the actual journey to Qūchān is certainly longer, as only the direct route (as the crow flies) between Gonbad-e Kāvūs and Qūchān has been calculated here.
Air line (approximately)
297 kilometers
160 nautical miles