The colour is due to the panel not the bulb, you could put blue bulbs in but all you will get is a faded orangy meh.
new dials were availble back in the dim and distant, but I'm not sure you'd find anywhere now, so you'd be looking for someone to make you a custom set. doable but not cheap. other issue is that all other lights in the car are orange too, so you'd need to scrape out the orange gel from behind the heater knobs and fit different colour gels there as well.
all doable, but a lot of faff really. someone like lockwood dials might be able to sort you out, they did a conversion dial for imports.
