There are no majic forms in real estate. The only important part is that it be in writing and spell out I agree to buy and he agrees to sell. Specify the terms, price, condition, etc. You would need to have consideration like ten dollars for the option to be considered valid as all contracts must have consideration.
I have seen sales contracts written on a napkin.
As a form you could just use a standard sales contract .
I don’t know if you are needing a lease option which is fairly simple or a sale leaseback which is done for depreciation type things for example, Sears has all their properties on a sale leaseback contract. Once the bldg. has lived its life out for the depreciation the can lease it back to themselves and it starts all over again.