Brookhouse volvo
https://classicvolvoparts.co.uk/car....S_1800E_1800ESwould be a good place to start, having worked on a few 1800s over the years be prepared to pay a lot for bodywork, these are structurally complicated cars to repair and body panels are pricey. You may have a problem getting a boot lid however the panel is not too difficult to repair. The interior for the early cars is unique and may also present some difficulty in obtaining seats and cards.
If you need anymore advice you are in the right forum.
JP