If anyone is interested in my input (I've owned a few Thunderbirds), certainly I'd like to see more colour choice. A few years back they did a limited run of deep blue (not Pelham) for the Japanese marketplace, so it is feasible for the paint shop guys to use a different colour.
At the end of the day, if you want a decent Thunderbird built from a myriad of choice parts and finishes, just buy a Lull.