This new "local agent" requirement has given me pause as my property manager has informed me that they will not be signing off on this.

Assuming all of the information you provided is in line.i.e.

Quote from @Matt Weddon: Really what generated this question was a section from Brandon and Heather Turner's Management Book, which has been incredibly informative and helpful.

Quote from @Jonathan Greene: That's very limited information for someone to help you.

I was considering reading J Scott’s “The Book On Estimating Rehab Costs” but wasn’t sure if the information remains relevant 6 years later given how pricing has changed since then. 

@Michael Baum thank you for all the good information.  

However, even up until the day before closing I was  never informed whether the title was Actually marketable or how and IF the liens would be paid off from the proceeds of the sale.        

Welcome to the community and be ready for a huge amount of information at your finger tips.

Ourcurrent approach involves identifying possible contact information for thelisted owners and calling multiple numbers, but this process is time-consumingand yields limited results.

I only brought this to the forum seeking information that would add value to the disposition of the deal.Thanks for the clarification.