I think this is one of the, if not the, biggest problems of running an old bike in the proper style. Other consumable parts like brake blocks, chains are easy to replace, or they don't degrade e.g. chainrings, so you can stock up on them or just use old stuff.
Yes, the Pasela is one of the very few black/amber tyres currently available, fine if you're looking for a wider and heavier tyre. I've got a pair of Michelin Axial Sports in black/amber on a bike, but I don't think they're made anymore. Also there was the wider Michelin World Tour, it was really cheap but gave a bad ride,. edit: just found SJS Cycles has them for 7GBP but P&P is 5GBP for 2 tyres, they're marked as 700x32 but they're actually more like 28mm. They've got deep zigzag grooves in the tread, and bits of glass, stones and other road muck gets stuck in them.
For narrow lightweight tyres, there was the Vitorria Open Corsa but that's been replaced by the Evo blackwall version a few years ago. A similar tyre is the Veloflex Pave, but I'm not sure if it's still available in black/amber.
Then there is the "Grand Blois" brand of tyres but they're very expensive, starting from 55USD+postage. I suppose the website/magazine (who sells these tyres) gets the tyres made for them by a tyre manufacturer.
Of course, tyre manufacturers can make tyres in any colours they choose, but for whatever reason, there seems to be endless combinations of colours except for black tread/amber sidewall. There was a discussion on another forum with someone who works for Michelin, apparently Michelin used a Paris fashion market research company and found out that people didn't like black/amber tyres!