Owner/Seller Financing for Apartment Building

[Ng Ib]

Hello everyone (particularly seasoned REIs), I came across a multi-fam. property listing in the Sun belt about a month ago. Owner is asking $650k. He's now open to seller/financing (wasn't originally). Owner will finance up to $350k with 300k down. I initially made an offer on the property, slightly above half the asking price based on my numbers. Property is barely 50% occupied with a lot of rehabbing needed from the information obtained so far.  (Sounds to me like the owner wants to get rid of it while making the best possible gain.) He's also requesting 5% interest for 120 payments. Kindly give your input, if you were presented with this "opportunity," will you venture in? If yes, how would you proceed? If not, why? TIA to any/everyone who responds.