Vacant multi family that needs full rehab

[Martin Shaw]

What all-in cost (purchase/rehab/holding cost) as a percentage of ARV is the most you'd consider for a full rehab on a 16 unit multi family that's been gutted to the stubs ( Owner is in bad health and after replacing roof has don't nothing else). Purchase is asking $150k and repair estimates are 250k (included everything possible and then some) for all in at 400k. My deal analysis shows Arv value around $800k plus. Is that spread enough and worth it. After refinance at 75% that's $200k plus a decent cash flow.

Thoughts?