"Booth, a native of Maryland, was a fierce Confederate sympathizer during the Civil War.
Sounds pretty Democrat at that time for me"
First of all, you didn't even prove he was a Democrat. And even if he was, that doesn't prove he wasn't a conservative. Democrats were conservative in the 1860s.
"We been over this, you should already know what the Conservative side was during Civil War. It was Lincoln's party"
In the 1860s the Democrats were far more conservative than the Republicans, but both sides were still pretty conservative by today's standards.
"Lincoln outright said the Republican party were Conservatives because they stood for conserving the Constitution the forefathers made"
Yes, they were conservative. And the Democrats were even more conservative.