I'll run with it since you seem to be genuinely interested in the answer and you appear to be engaging in good faith.
I will assume your question involves finding myself suddenly in an entirely phenotypically male body rather than one that has only experienced a short period of exposure to low levels of endogenous testosterone and then decades of oestrogen therapy.
You mentioned 'retaining its character and memories' and talked about having a male ID which is quite a different scenario to mine, more akin to some kind of mystical ghostly possession of an existing fully grown and intact person than a hypothetical (fanciful but potentially achievable within the realms of known physical laws) body transplant. Quantum Leap rather than Ghost In The Shell.
So I'm possessing someone's body, who I'm presuming I can be confident is metaphysically 'dead' even though I can access his memories and personality and thus there's no ethical consideration about ownership etc etc, and I'm presuming similarly there are no close familial or romantic connections to avoid that entire can of worms.
I know for a fact that I am a mind that experiences gender dysphoria in a phenotypically male body. I know that this feeling gets worse over time when untreated. I know that I have absolutely no interest in interacting with society as a man while being perceived to be male, and that it will cause me great and debilitating distress if this is something forced upon me. I also know I have no interest whatsoever in pretending to be someone I'm not.
I'm going to be honest here; I'm not sure I survive more than a few months of this. That's a pretty grim state to be trapped in, especially while living with the trauma of escaping it once.
However, perhaps I'm feeling particularly masochistic and bloody-minded and decide to effectively start again in adulthood without the benefit of the treatment I fought so hard to get in my childhood.
I would alter my ID to F because it accurately reflects who I am, the journey I am on, and its destination
I would ask people to be sensitive debating my existence because I've already been on this journey once and it was horrible enough the first time. Obviously they won't listen - they didn't the first time round - but I can at least ask.
I would make use of whatever means exists to make this body as tolerable as possible.
I would be extremely careful about how I use single-sex spaces knowing that my impact on other people using them will be perceived quite differently and harm could be caused in ways that my previous body would not cause.
In having chosen to medically transition it, I would know from experience that any male social privilege this body would otherwise grant will immediately be rescinded by the patriarchy - and I would find little refuge amongst many different groups of women who are hostile to trans people. Even those who might otherwise be sympathetic are likely to be significantly less so now. There's only one community that is likely to provide refuge.
I almost certainly would not pursue sexual relationships at all - I think the dysphoric grief it would be likely to trigger would be far too distressing. I'm sure for some people it would all be a fascinating novelty but for me it would be going straight back to pure hell. Mercifully, I know that transitioning would spare me from a male sex drive at least, though it would be horrible at first. Since current waiting times to access CSH are measured in half-decades via the NHS, that's an incredibly long time to have to endure.
Gosh this is just a very sad, depressing thing to consider really in light of my existing life experiences.