Got an offer from another company but stayed in my current role through an acquisition with future conditions, how do I proceed?

I recently had an offer for a new position that paid about 10k more than I currently make. I went to my boss with this and all of upper management got involved convincing me to stay. We were being acquired and they said that once the dust settled then I can be a big part of defining my role going forward and we could discuss pay as well. I probably should’ve gotten something definite in writing but I didn’t think that would be possible in the middle of an acquisition (the final papers were signed the week after this discussion).

Well we are now about 4 months into the acquisition and I feel like the dust has mostly settled. My issue is I don’t know how to initiate this conversation and what a reasonable ask for pay increase is.

I currently make 70k as an engineer and got an offer for 80k, I also want to change my job role a little bit from what I currently do. Would asking for them to match that 80k offer be too much? Any advice on opening this conversation without coming off negatively to management?

Thank you in advance