$495/mo in cashflow. Am I missing anything?

[Joe Fornasiero]

I've recently found a duplex that I'm interested in purchasing the list price is $69,000 but I believe I could purchase the property for $60,000. Current rents at $600 per unit totaling $1200/mo. The tenants are up to date on rent payment and have both lived in the property for 5 years. The home was built in 1925. I was informed that all systems (electrical, plumbing, etc) are up to code and the home is in good condition. The home is in a B/C class neighborhood 1 mile away from a very large employer and 3 miles from a college campus. Based on the 50% rule I would cashflow $375/mo with PM and $495/mo if I self manage. (20% down) Does the maintenance percentage change with an older home like this? I want to make sure I'm evaluating the property properly.