if i were moving my primary to a gmail account, i'd setup the "send mail as" thing to receive all the email in your new account, set-up a filter to automaticall

if i were moving my primary to a gmail account, i'd setup the "send mail as" thing to receive all the email in your new account, set-up a filter to automatically label it as such, and then set a super strong password w/ 2FA on your previous acct.