I am sure you mean HWY 65 not 75.
I have not taken HWY 412 but have driven HWY 62 many times. Either way you will end up on the southern part of 65. That part does not have the 3 hills you are talking about.
If you have never stopped in Eureka Springs this would be a good time. Its worth a day or two.
Good Luck love the ozark mountain driving
Itasca Meridian SE 36g
Road Master Tow Dolly