A few comments peripheral to your question, which I can't answer directly.
This would be a good time to do any desired additional air sealing and insulating, so that the equipment can be right-sized for the new conditions.
If you have any information on how the existing system was performing, it will be helpful in sizing the new system. For example, if when running properly (e.g. new), the system was not running flat out on your hottest/coldest days of the year, then it was oversized. E.g. if it's a 3 ton single stage, and on the extreme days of the year it never ran more than 2/3 of the time, then a 2 ton single stage would be adequate.
Lastly, as far as I know the principal difference these days between a central system and a "mini-split" is the exhaust airflow direction of the outdoor unit. Central systems generally pull in from all sides and exhaust upwards, while mini-splits exhaust sideways. That is, all the big mini-split brands offer "high-static" indoor air handlers that can be used to feed existing ductwork, rather than install individual heads in each room.
Cheers, Wayne