I doubt these would fit without possible redrilling and/or rewiring. They might fit dimensionally, but who knows. Would probably be easier (and cheaper) to get new seat covers that mimic the newer style & reskin your interior
The seats on my '09 weren't hard to R&R, so I would take the driver's seat out and compare them. I replaced mine with a set of older seats that were otherwise the same, but I transferred the seat modules to eliminate issues with electronic compatibility. The modules connect to airbags in the seats, so electronics is a biggie. Disconnect the battery before disconnecting anything to avoid triggering a SRS fault.
I'd take that project on in a heartbeat!
the airbags and occupant sensor will be your issue, since it's a different model year it's going to be incompatible due to wiring differences. Worst of all newer modules are coded specific to the VIN and this could brick your seat module, worst cause issues with the CAN bus.
I've never taken the Volvo seat foam off but just like other cars that shouldn't be really tricky the bottom of the seat will be the easiest and the backrest will be your most intricate depending on how Volvo attached it to the actual foam to the frame.
I really think it. Can be done if you have the time! The money portion is already taken care of it looks like with getting the SPA seats.
Only thing I'm wondering about is the airbags not the connections but the actual airbags themselves if they are a different size different bracket holding them on exc...
Your going to have to take both sets of skins off the seats to probably swap airbags just an FYI