Awesome find @jamesinc
The big one is wheels. 700 & 900 wheels fit, and often look great.
Later model wheels can fit though spacers are required to achieve the correct offset.
I think the 740 clear side indicators would fit, never tried it. They could be a cool upgrade. Peel off the Volvo badge on the front guards and fit them in the holes there. Wiring would not be too hard. I think the 90+ 240 models had them.
Rear brake calipers from an 850 fit a 240. I have a set on one of mine, generally because 850 calipers are younger and more available. They are a touch different, I think the hard line had to be bent a little though otherwise a straight bolt on. Just a brake caliper though, no performance improvement.