I agree with everything but #7. When he comes - he must
continue a short space. But not Galba, the seven months you are saying.
What it is talking about is king #7 is the king that will be mortally wounded, but he comes back to life for a short time of 42 months - as the beast.
Galba would not match up with Revelation 12, either, because in that chapter the seven heads have their crowns. And that chapter 12 has the 7 years contained in it. When it gets to chapter 13, with 42 months in it, the seven heads no longer have their crowns, which the last of the seven kings has been killed.... although at the beginning of the 7 years in chapter 12, he has his crown. So the person is the seventh king at the beginning of the seven years, but will be killed right before the 42 months begin, and comes back to life (continuing the short space of the 42 months).
Take a look at those crowns/no crowns in each of the three chapters 13,12,17.
Revelation 17:10 And there are seven kings: five are fallen, and one is ,
and the other is not yet come; and when he cometh, he must continue a short space.