partnership with spec house builder

[Bill McCoy]

I have two ready-to-go lots in good location. A spec house builder with a good track record (25+ SFRs in small local community over last 8 years, all sold and some since resold with good appreciation) some access to bank financing) proposes to partner with me on the following general basis: I supply land to the deal at fair value, I supply all the hard money for construction at 12%, we split the profit or loss from sale 50/50, they act as GC on cost + 2% basis. The upside for me per their proforma (less risk-free return on my money) would be roughly 50% boost over what I would get by just selling the lots. Obviously this would require a considerable amount of trust that they would see the project through and also that they would not be padding payments to subs but aside from the trust factors (which could be mitigated to some extent by appropriate legal terms) does this seem like a reasonably fair arrangement? Local market is very strong now but could be nearing the end of cyclical boom so there would be downside exposure but if I ended up having to carrying one or both homes for a couple years that wouldn't be outrageous.