Equity kicker in exchange delayed financing funding

[Jake Fugman]

Hey all, 

I'm considering lending cash to a flipper friend of mine so he can make a cash purchase on a $200,000 deal which is requiring certified funds.  His plan will is to obtain delayed financing ASAP after purchase so he can pay me back in full w/in 1-2 months.  Assuming he plans to flip the property after a 6 month rehab I anticipate he will make approx $50,000 - 75,000+ after selling/closing fees.  

Has anyone ever offered taking equity/percentage of the final profits VS interest or points?  In this case if I would likely ask for 10-20% of net profits when property is re-sold in 6-12 months.  Too much? Too little?

Any ideas or examples are appreciated!