first things first
a standard clutch is Valeo, easy enough to get hold of at reasonable prices, from the usual places. Seen as you are doing the belts as well, you mat be best off taking the gearbox and engine out as one.
145 specific stuff is the condition of the wishbones, listen for clonks and the car wandering despite the steering wheel being still, check the floor pan for rust (in fact make this the first thing you do) not obnious as it hides behind the underseal which does an excellent job of hiding it. Wipers tend to be noisy, new linkage if wobbly, radiators are fragile, watch for the relays in front of the battery, also, big watch out is the red key, confusing as the regular keys are red, but you need to ensure the square shaped burgundy key is with it. The rest is pretty straightforward. Alloy topped engines feel like they have more pep despite being down by 5bhp.
Fitting leather is easy, finding it is not, and join the queue.
Most of all it should feel like a go kart, very direct steering, somewhat harsh ride and good pick up, they are great fun and very under rated.
Do you have a link?