The car you're looking at looks really nice, Volcano orange is quite a rare (and great looking colour). Sports packs included the following from new:
13x6 inch Minilite style wheels (originals were made by Speedline)
Wide body coloured arches
Upgraded Koni dampers (to cope with the increased weight of the bigger wheels)
Twin fog lamps up front, two spot lights (which switch on on full beam)
A modified steering rack, to limit the lock so that the larger wheels don't foul the bodywork
Cut-away arches for the bigger wheels (done at the factory)
Voltmeter
Oil temperature gauge
Chrome tailpipe finisher
Drilled alloy accelerator pedal (which was standard on the Cooper anyway)
There were definitely wheel spacers fitted, but I don't know what size
There are a lot of 'fake' sports packs around which have some of these fitted (such as the wheels and arches), but a genuine sports pack would have had all of these fitted from new. Some cars also had the wheels and arches fitted at dealers etc. I think around 50% of Coopers had the Sports pack option fitted new, but so many have since been converted which is why they seem so common now.