180 Days Job Portability rule on I140 Amendment

Originally I have a EB2 I140 with Employer A few years back and Later Employer B acquired Employer A.
I am planning to apply for I140 SII Amendment and downgrading the category to EB3.

Want to understand how the I140 Job portability works in this case. Will the 180 days rule still applies and Employer can withdraw my I140 amendment once approved before 180 days ?

If you file i140 EB3 downgrade as an amendment, then you risk both EB2 and EB3.

Its better to file EB3 i140 as a new application.

Thanks for your response.
As it is I140 SII , Attorney said it would be amendment and will ask EB3 Category.
And If the dates in EB2 becomes current, He said he can file another I140 SII Amendment for EB2 Category.
In SII cases, They said, it would be an Amendment only…

I suggest to file EB2 amendment then instead of EB3 and then file EB3 downgrade at the time of filing i485.

Offcourse, if employer and attorney agree to it.