That should leave you with a quality and lasting finish productJust be sure when getting your estimate you and your contractor you are aware of exactly what work he plans to perform. 

The plan would be perform improvements and refi out, returning my grandparents money in 9-12 months.How would you go about structuring a deal with this scenario?

OSHA can perform a random walk down of a residential home but they often will not.

Along with hired workers he will be performing the rehab.

Going in my plan was to spend about $45k and 3 months and the Hope was to refi for $200k+ to pull out $145k and then rent units for $600 each, and cash flow around $500-1,000 each month and pull out my cash investment and in essence have a performing that I had only $10k-ish of my cash invested after the refi.

Our 4Plex is performing great and it has been the best move we have ever made!

Identify what you do the best out of all the tasks performed on this flip and same for your partner.

People think I'm crazy for having an accounting degree and wanting to move away from traditional W2 income into performance pay.

Not to discourage you but doing flips from afar is no easy task and opens you up to other risks associated with those logistics you would not be exposed to otherwise.

I figured the 1b1b perform better throughout the year where something like a 3b3b performs better at holidays, but as a whole which performs better.