SOLVED. Sci-Fi. A man from far future exchanges consciences with a modern man. [s]

[Bored]

Using some sort of machine man from very far future exchanges consciences with a modern man. I think the selection was an accident. Generally, he does it as a method to study/experience other time periods and cultures.
He is some sort of royalty or very wealthy.
On the other hand, the conscience of modern man left to try to figure out how to continue to pretend to be another man. This proves to be very challenging and a lot are in stakes. I think there was a bride involved and possibly galactic war.

[Bored]

I believe that I've read around the late 1980s printed in some sort of magazine. There was some fleet destroying superweapon

[Ayshe]

The Star Kings maybe?

[Bored]

Oh, Lord. I think you got it. All the summary, plot lines match. Even the names sound somewhat familiar!!
Let's mark it as solved!