Discounted Note Opportunity

I ran across an opportunity that could be lucrative, but all the planets would need to align, etc. It's for a discounted note. Here are the details:

Initial Amount: $120,000
Interest Rate: 6.5%
Term (Months): 60
Monthly Payment: $2,374.94

There are stil 15-16 payments left on the note, so an opportunity to gross almost $38,000. I am thinking of offering $15,000 for the note, but not sure if that will be enough. If so, the ROI could be enormous - especially, if I can get one of those short-term, no interest, credit cards, which I could essentially use for a interest-free loan. Even if I can't go that route, the worst I could do is take out a loan against my 401k, which would still make things attractive. Assuming I can buy the note for $15,000, and the remaining term is 15 months, I can get a 401k loan for one year and pay about $1,317/month. So, I'd be cash flowing to the tune of $1,058/mo for 12 months and $2,375/mo for the last 3 months, for a total of over $19,800 in net profit for 15 months. There would still be some other fees associated with acquiring the note, but I could pay for that out-of-pocket. Even if the out-of-pocket expenses are upwards of $5,000, I'd still have an annualized ROI of 271%.

Again, I hesitate to even talk about the opportunity as there are a lot of things that need to happen in a precise way for all this to work. The first thing is to do more due diligence to make sure everything is correct.