Paid off Rental property- 100 years old. Next steps

Hey all, 

I have a paid off home in historic downtown Flagstaff nearing 100 years in age (1930 build). I am exploring options between :

1) Keeping as long term rental and using HELOC to obtain other properties while dealing with potential maintenance of a 100 year old house

2) Selling and purchasing new property (STR or LTR) in better condition with the goal of having a higher cash flow.

The house is worth approximately 650-700k (Developers in the area may offer more). It is renting for 2100k/ month with no mortgage.  I would love to hear if someone has had a similar set of circumstances or opinions on a best method to grow and scale with this set up. Thanks!