Ok since I'm sure not a M70 expert and don't own a M70 to check. Will a short action M70 classic action fit in a M70 PF stock?

If they are both short actions yes. The older push feed gun in 243 and 308 calibers were actually long actions with a spacer in the magazine. The first short actions Winchester did were push feed then came the Controled round feed classic and the controled push feed actions. These include the WSM actions. All of these are same length and with very little fitting stocks will work for each other. The WSSM action is shorter than the short actions.