The war stopped with Israelis "winning", if the imposed cease fire had been a little later the Israelis might have much more if not all of Jerusalem and the surrounding areas, random bits of the west bank. Those were all in the Palestine Mandate. Perhaps some of Gaza as well. Taking bits of Syria (Golan), TransJordan (Aqaba), or Egypt (some of the Sinai) might have be militarily possible had the conflict continued a little longer, the politics of the Jews taking territory belonging to another sovereign state as opposed to a bigger piece of the Mandate pie would be very tricky. There would be a lot of pushback from those who supported Israel, and I doubt the Israelis would have attempted to take territory they knew they'd have to give back. Temporarily holding some bits of "foreign" territory pending an armistice or some formal agreement is possible, but outright incorporation, which would have been the fate of any Mandatory territory unlikely.
The Israeli position on the post war lines was that the Arabs had rejected the partition plan, and now that they had lost militarily asking for a return to those lines was a non-starter.