In need of $75k renovation loan from private lender - easy deal

[Austin Smith]

I'm working with a seller who I happened to know and he's allowing me to partner with him to raise JUST the renovation budget to then flip or refi. 

Now there is a mortgage for about 150k left on the house, yet multifamily-house is currently worth around 250-300k in it's current condition.  With $75k rehab, it will be around 400k ($375k appraisal in hand).

The issue I'm finding is that most lenders want to be 1st on the debt instead of the current mortgage holder.  

Will be this be everywhere I go? I just need to raise the rehab budget. Any thoughts or suggestions ?