I've got some of the original aluminium flame-resisting paint, courtesy of Clive Elliott. Way past the end of its shelf life but amazingly still usable after being left upside-down for a month followed by half an hour with an electric paint stirrer. Nothing else I've tried has quite the same finish. However I've only got enough to use where it can be seen such as interiors, so I'm experimenting with a substitute for the Abbot's engine bay. Smooth Hammerite looks quite reasonable when brushed, there are a few brush marks but I expect them to go after a second coat.
Andy