TWR-K60N512 board is using K60 100MHz product silicon1.x; TWR-K70F120M board is using K70 120MHz product.
Kinetis 100MHz is using different silicon platform with Kinetis 120MHz product, there are some modules exist difference, such as MCG (clock) module.
I would recommend customer to refer Kinetis 120MHz baremetal example code below:
KINETIS_120MHZ_SC : Kinetis 120MHz bare metal sample code.
K70_120: Kinetis K70 Graphic LCD 120/150 MHz MCUs
Wish it helps.