I think if you want to do old/historic homes you need to be in areas where the majority of homes fit this category. Seems to be a lot comments from folks in California where the housing stock is much newer. Not trying to be offensive, but it seems like a lot of folks are making comments on the historic market from markets with almost no historic houses.
For example, if I ever used Vinyl on project it would sit there like a big fat log. All of the projects around me are either going to hardi board or back to wood. It's one of the first things our buyers are looking for and if you are out of step with the neighborhood the house is going to look like dirt.
If you look in markets like Brooklyn, NY or Cambridge, MA you can certainly make a living doing this kind of work. But be prepared the capital investment is on a totally different scale.
Acquisition prices will be around the million dollar mark. Renovation costs will be in the 500k to 1MM range and ARV is going to be north of 2.5 mm to make this worth your time.
Seems a lot of people in the flip business are more focused on the median home in their area (which is smart). So if you want to do historic stuff you need to be in a place where the median home will support what you want to do.