You could check out our two single-family residential investment models:
https://www.adventuresincre.com/single-family-residential-investment-analysis-model/
https://www.adventuresincre.com/excel-pro-forma-for-flipping-houses/
With that said, I’d recommend you consider using Spencer’s Value-Add Apartment Acquisition model. In your case, you’d be underwriting a 2-unit multifamily project. I suggest this model because it will provide far greater flexibility and sophistication, and won’t take much longer to learn then the above-linked models.
https://www.adventuresincre.com/a-cre-value-add-apartment-acquisition-model/
Spencer has built a large collection of tutorials for using the model:
https://www.adventuresincre.com/value-add-apartment-acquisition-tutorial/