Chris,
Consider a getting set of standard steel wheels from a 940 to fit with new tyres- they’re 15 inch not 14 which means it’s a lot easier and usually cheaper to get hold of tyres- the reduced sidewall height will help sharpen the steering and handling slightly too. 940 wheels are the same bolt pattern and offset, so will fit straight on.
Otherwise- does your son want to learn to weld? If so working on the car could be a perfect opportunity. Although it’ll depend on whether you have the space for it etc.
I recommend you encourage him to set up a thread here in the project cars section and also on the retrorides website- project threads are an easy way to keep interest up as people comment on them and offer encouragement etc.
Other than that, clear the sills out (they’re always full of leaves and other debris), check the car carefully for rust and start a to-do list of little jobs that need doing
Edit- one more thing, soon as you get the car take the wheels off in turn and carefully clean the calipers out and push each of the pistons back a bit to check they aren’t seized- each one should push back smoothly with a bit of force applied. Also clean/replace the caliper mounting pins to make sure the pads can slide easily on them. A stuck piston or pad mounting pin will mean that brake pad doesn’t release, leading to over heated fluid, warped discs and poor fuel consumption... Whilst there check the brake pads for wear, the piston dust seals are in good condition and the flexible hoses are in good condition with no cracks or bulges.
Cheers