plan to visit Yunnan and Guizhou in late November and plan to travel from Kunming to Anshun

I don't want to take a train because the trip lasts longer than reasonable and none of the running trains is conveying Soft Class. Hard Class trains in China are not to my liking.
I realize that there is a high speed highway connecting the two cities, can you possibly advise the total road distance and if there is a bus running on this stretch? According to my estimations the distance should be around 385 km. and driving time no more than 5 hours (against 541 km/8 hours of the train, respectively).
Thank you for a quick reply