Skyrocketing isna bit of hyperbole with rates still on the very low end historically.

There are a large number of older and even historic properties out there, and I imagine only a small number of them have been renovated up to current standards, So whether you’re renting it out or flipping it, if they look and function beautifully I think they’ll be in demand.  

Cincinnati is known for its historic architecture.

As these types of investments were historically put together and run by very experienced people / companies Not someone who is pretty much a beginner in real estate with no real body of work behind them.

How much more appreciation can I expect on any of the historic bungalows that were built in 1920?

I do not know anything about your local market BUT . . . in this era of historically low mortgage rates, do you really expect to find a sufficient number of buyers out there willing to pay 10% P&I? 

Yeah, we're in a benign credit environment and defaults are near historic lows. 

Being an investor in an older historic area (Savannah), I come across what we call death houses all of the time.

Even though cap rates for MHPs and RVPs are historically higher than other asset classes, I have found really good deals with lower cap rates, but with a lot of upside. 

Also, there a several pockets of St Pete that are in historical districts even if they don't seem to be.