IMO comparing who’s liberal and who’s Conservative in the 1860s, today’s Democrats, today’s Republicans vs. Democrats and Republicans in the 1860s is a waste of time. Go ahead it you like. But remember, it was a Republican administration in the early 1860s that passed legislation to build the intercontinental Railroad system, the Homestead Act, the Morrill Land Grant College act, the first income tax and the first conscription act in the United States. Your view may be that these are “conservative, Republican agenda items, others could argue that they were liberal to the max.
A standardized, intercontinental railroad system just made sense - then as now. The democrat solution, as practiced in the south, resulted in an inferior patchwork series of unconnected regional lines of different gauges that hindered productivity.
And I would hasten to add that, although both the union income tax and the conscription acts technically started “up north”, they were quickly emulated and expanded upon by the con-feds. Good for the goose?
That's in line with what Republicans have always done. US highways came in under Harding. The Federal Radio Commission (forerunner of the FCC) and Hoover Dam were authorized in the Coolidge years. Eisenhower gave us the St. Lawrence Seaway and the Interstate Highway System. For better or worse, Republicans have often favored public works, internal improvements, and support for industry.
I'm not sure how 19th century political divisions can be mapped on to 21st century ideologies (or vice versa). So much has changed. It's similar with earlier divides. We are all Jeffersonians and we are all Hamiltonians. Pure ideological types are hard to find and not favored by difficult political realities.
What I do know is that it would be very bad for Republicans and conservatives if they some day proclaimed themselves to be the heirs of Calhoun and Jefferson Davis and the other pro-slavery politicians of the 19th century. It would be a bad thing if we obsessed about the legitimacy of the Homestead Act or Land Grant Colleges to the point where we threw in our lot with the fire eaters and Copperheads.
Conscription and the income tax were temporary emergency measures that ended with the end of the war. They were also a part of Confederate policy, not just Lincoln's or the Republicans.