How could I structure this deal?

[Peter J Marshall]

Hey guys

I have another investor who possesses a property I wish to buy. This property is in distress so I desire to brrrr it to make my gains. The current investor/ owner would be willing to be paid out at completion of rehab.i would be funding the rehab with finances and sweat equity . Upon completion refi* / pay there asking price at this time, in turn I would become sole owner.

My question is , how could I structure this deal to be protected legally for my investment? Would I have to do a lease option and then act on the option at refi* time? I just want to have a some legal backing to cover my financial investment? Please could some one shed some light on this matter for me?