A contract for a software

I want a contract with a prospect for my small software project that I'm offering as freelancer. Its code is more generic and some customized to the user requirements, and it should be able to be sold to other prospects too. Since FL site I’m using has a general purpose agreement that gives all rights of to buyer (however they are OK with custom contract so I can retain rights). Since its a small project one time so would a basic 1/2 pager agreement may suffice? Not sure its more of IP or NDA.