How to evaluate a property with permit to subdivide

[Tom L.]

Good afternoon - we have a lead on a single-family cape house on a .25 acre lot in Hicksville, NY (Long Island). The owner recent received a permit to subdivide into two lots. Doing so would require tearing down existing house and building two new ones. My question: what's the best way to value this deal for immediate purchase. Should my offer price be based on just the existing house and property, or the future potential as well? Thanks.