The item that has been near the top in all recent 'wanted' polls is the class 120 DMU. I would certainly have a Scottish (Inverness) one (or 2) if produced. It could also be a lead into other long frame DMUs, 119, 123, 124....
The 120s were very well travelled, the Southern region being about the only area that they never really penetrated, although they did regularly get to Pompey and Weymouth.