Why dont you just try the latest bios? Neither of those are the latest. There is one from october. As far as the ME is concerned, I just think it may throw an error if the new versions of ME FW are on a different security version number. i.e. 11.8.71.xxxx cant downgrade to 11.8.70.xxxx as far as I understand it. If it does cause an issue, I'm sure the people over at winraid can lend a hand. Extremely knowledgeable with bios/firmware and there is a repository of ME FW there. Plus, there is an even later version of ME FW that was just put out a few weeks back which asus doesnt even have in a bios yet. Youll have to flash that yourself if you want it.
edit:
as far as actual ME FW versions go, there was a 11.8.65.3606 from july 2019. Then there was 11.8.70.3626 released in september, and then the latest 11.8.71.3630 released just a few weeks ago. However, you can still be on 11.8.70 and still be not vulnerable to the various vulnerabilities out. Confirm by running InSpectre again, as well as this tool from intel.
https://downloadcenter.intel.com/download/28632/Intel-Converged-Security-and-Management-Engine-Intel...Download the windows version and run the GUI folder exe. It will produce an output