This is said of Paul: "And he went into the synagogue, and spake boldly for the space of three months, disputing and persuading the things concerning the kingdom of God" [Acts 19:8]. And "there came many to him into his lodging; to whom he expounded and testified the kingdom of God, persuading them concerning Jesus, both out of the law of Moses, and out of the prophets, from morning till evening" [Acts 28:23].
It is too simplistic to say "Paul preached grace," as if it was something distinct gospel from that of the Kingdom of God. Paul evidently thought preaching about the grace of God was akin to preaching about the Kingdom. He told the Ephesian elders [as recorded in Acts 20:24,25]: "But none of these things move me, neither count I my life dear unto myself, so that I might finish my course with joy, and the ministry, which I have received of the Lord Jesus, to testify the gospel of the grace of God. And now, behold, I know that ye all, among whom I have gone preaching the kingdom of God, shall see my face no more."