Those aren't real switchbacks on 14A, just a few curves with a 200ft radius. If you can keep your speed down to 25 mph on a 10% grade, you will be fine.
https://maps.google.com/?ll=44.799317,-107.961026&spn=0.003738,0.008487&t=h&z=17&layer=c&cbll=44.79937,-107.961126&panoid=zHYAX7n9TYJrC-0Br2HuiA&cbp=12,270.41,,0,4.89https://maps.google.com/?ll=44.795472,-107.950019&spn=0.003769,0.008487&t=h&z=17&layer=c&cbll=44.795555,-107.949979&panoid=3aGHb9SIif335Ylgi84TwQ&cbp=12,26.1,,0,0Old Hwy 14A is still visible in the Sat view to the north. It has tighter curves that qualify as switchbacks. It also is longer, so has a lower average grade. That is often the case, since old cars had lower power to weight ratios.