Based on this question/answer it seems that the FARs in relation to turbulence handling have been updated several times over the years. Does the Boeing 737 MAX conform to the latest FARs or to the FARs in place when the Boeing 737 was first certified?
Testing standards for things like turbulence and fatigue are not related to any specific aircraft type certificate. Yes, the MAX shares the same type certificate as the first 737-100, but the TC only makes reference to the certification standards to which the design complies. If you look at the TC you will see that it references the advisory circular for fatigue and damage tolerance testing (AC 25.171-1x), but as new models are introduced the TC makes reference to the latest version of the AC at the time the modified TC is issued to include the new model. The latest version of the AC is -1D.