My initial thoughts would be to secure a construction loan for the total rehab amount based on the entire property's ARV.

Assuming you can cover a decent portion of the $60K from the 401K loan, get some sort of loan for the rest.  

Conventional loan How did you add value to the deal?

Further, how do I demonstrate proof of funds on a HELOC (ie, the equivalent of a pre-approval letter for a loan)?

I would like to report Xplicit Home Loan (https://www.xplicithomeloan.com/) for fraudulent activity.

He couldn't sell the property because no bank would give a loan on it with that in the contract.2.

I have a cousin in Florida that is moving and would love to come to an agreed price on their place but just take over the mortgage instead of securing my own loan as I am looking for it as an investment and would be required to do 20% down (which I would not have). 

I was one of the four original investor to raise capitol to get the loan for construction.

I then negotiate with the borrower a plan for repayment or I foreclose.

I have 20k saved and plan to use an FHA 203K loan and house hack to net zero/cash flow minimally on my first investment.