How to determine ARV on a multi-family property?

[Scott Champion]

I may be getting the opportunity to purchase a 6 unit apartment complex, all being 2 bedroom 1 bath apartments. I think I have good idea of how to determine this number in single family houses but struggling with the commercial ARV. These apartments are in a great location, inside a small college town, but they need a tremendous amount of work. They are all unoccupied and have been for several years. I'm estimating a rehab cost of approximately $300,000.00 or a little more. I need help figuring out what I can pay to still come out with cashflow at the end of the day. There is a 39 unit apartment complex (all 2 bedroom 1 bath) in the same small town, renting for $750 to $850 each based on the individual apartment updates. This 39 unit complex is completely full with a waiting list. The location is near Shelby North Carolina. I hope this is enough information for someone to help me out!

 Thanks in advance,

Scott