Yes, I've done it. I even interchanged the two adjustment knobs -- back angle knob and lumbar support adjustment -- and patched the hole in the side. (When Volvo made the seats, they punched a 3-sided "D" shaped hole for the lumbar knob. I folded the vinyl back into position and glued a support cloth behind it. Worked great.)

You MUST flip-flop the big knob (seat back angle) because it will otherwise conflict with the e-brake console. Easy to do.

As an alternative, you can install good foams into your existing seat frames and not worry about the left-right issue.

Before you reinstall the seats, be sure the four bolts securing the backs to the bottoms are socked down solid.

This is also a good time to repair the bun warmers, if needed.

--
Don Foster (near Cape Cod, MA)