Co-signer ROI question

[William Hiday]

Scenario:

I happed into and ultimately picked up an off-market rehab in a very hot area for about 20% of the what it appraises for.  It will be a total gut job and the renovation will cost $125k+ and take four to five months to complete, but it will be well worth it as the profit could very well touch six figures.  Given my background as a custom home builder and remodeler, the construction phase isn't that big of a deal.  

With regards to the construction loan, the crowdfunders don't want any part of it, but the bank (local savings and loan that I have a relationship with) said that they would..... IF... I had someone co-sign the loan.  I have three interested parties (I've known them all for 30+ years) and they're all asking me what the deal looks like.  Ie: what's in it for them and how much do they stand to make.  I'd like to just work with one of them (all three are very well-qualified) on this deal.

How do I set this up?  Give them a x% return on the loan that they co-signed for?  Give them x% on the profit that is made?  The ball is in my court to come up with the terms.  I'm just not familiar with what the expectation is, from an investor's standpoint, on a deal like this.  Could anybody help a meager old hammer swinger structure this thing?  Thanks in advance!

[Hunter Thompson]

@William Hiday If you came to me and simply asked me to co-sign and have no involvement. I can't imagine expecting more than 10%. Especially if you were able to show me that your profits are potential six figures.

 Of course, this is just my opinion, and I am assuming there is a lot of trust in the partnership.