As noted below, Volvo had rebuilt leatherette panels available at one point, exchanged on a core. They were actually "perfect" replacements. I can't imagine why Volvo stopped doing this. Or maybe I can.

I'd suggest buying the kit and farming out the repair to an automotive upholstery shop, since the skills for completing an engine swap (they don't actually rebuild B5234Ts in the back of your dealer's service department, that's usually done in a plant in Sweden) and doing upholstery work are not quite the same.