@Scott Schultz highlights the point I was trying to make. You have to be careful looking at current tax records. Is the townhome currently owner occupied? If so, the current tax records probably have exemptions that rental property does not qualify for.
Again, I am not familiar with GA property taxes, but I will use an example from Indiana. A SFH owner occupied will run about 1% of market price. The instant that SFH is turned into a rental property the tax rate jumps to 2%. If I relied on the tax records that the previous owner paid, I would be under estimating my taxes and could turn a good deal into a negative cash flow.
You mention that your numbers are conservative. I don't think you are being conservative at all. I think they are right on with what you will be paying for a rental. The property management fee is lower than what we see in Indiana. Typically, 10% of gross rents plus tenant finders fees are charged, if you want full property management.
I hope this helps. You know your market better than I do. Good luck and I hope it works out for you.