Need advice on buying bare lot that hasn’t been sub-plotted.

[Account Closed]

I need some direction guys and gals... I have a bare lot I’m hoping to buy, decent price, decent size and within city limits. Owner and I have an agreed-upon price. Problem I’m having is, in talking with the city, utilities and access road (along the easement) need to be installed prior to sub plotting the parcel. I need some help on writing up a contract to where if I put out all the money for that work, the seller can’t back out, and at the same time have the negotiated price put to paper.

Any help with this would be appreciated. Thanks!