The current thought is that black should have an advantage in all lines. For the sake of completeness, I have made this minor section.
A: 8.d3?! dxc4 (8...Bg4 9.Qd2 Bh4 may be even stronger) 9.Kxf2 Bg4 10.Qd2 0-0-0 11.Nc3 cxd3 12.cxd3 Rxh8 and black is slightly better.
B: 8.Be2?! Bb6 9.d4 (9.d3 Qc5 10.Qe1 Bg4 11.Nc3 0-0-0 and black has the advantage; 9.Bh5+ Kf8 10.Ke1 Nxe4 11.Qf3+ Kg8 12.d3 Nf6 13.Ng6 Qc5 14.Nc3 Nd4 15.Qd1 hxg6 16.Bxg6 Bg4 and black has the advantage) 9...Nxd4 10.Bh5+ Kf8 11.Bg5 Qc5 12.Nc3 Nxh5 13.Qxh5 Be6 14.Qxh7 Nf3 15.Bh4 dxe4 16.gxf3 Bh3+ 17.Ke1 Qe3+ 18.Ne2 exf3 19.Be7+ Ke8 20.Qg6+ Kd7 21.Rd1+ Bd4 and black wins. This is mostly untested though, few games have been played with this variation.
This section deals with any variations other than 8.exd5 and 8.Bxd5 after
1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.Nxf7 Bxf2+ 6.Kf1 Qe7 7.Nxh8 d5
The current thought is that black should have an advantage in all lines. For the sake of completeness, I have made this minor section.
A: 8.d3?! dxc4 (8...Bg4 9.Qd2 Bh4 may be even stronger) 9.Kxf2 Bg4 10.Qd2 0-0-0 11.Nc3 cxd3 12.cxd3 Rxh8 and black is slightly better.
B: 8.Be2?! Bb6 9.d4 (9.d3 Qc5 10.Qe1 Bg4 11.Nc3 0-0-0 and black has the advantage; 9.Bh5+ Kf8 10.Ke1 Nxe4 11.Qf3+ Kg8 12.d3 Nf6 13.Ng6 Qc5 14.Nc3 Nd4 15.Qd1 hxg6 16.Bxg6 Bg4 and black has the advantage) 9...Nxd4 10.Bh5+ Kf8 11.Bg5 Qc5 12.Nc3 Nxh5 13.Qxh5 Be6 14.Qxh7 Nf3 15.Bh4 dxe4 16.gxf3 Bh3+ 17.Ke1 Qe3+ 18.Ne2 exf3 19.Be7+ Ke8 20.Qg6+ Kd7 21.Rd1+ Bd4 and black wins. This is mostly untested though, few games have been played with this variation.