Hi,
I've been using a variety of paints recently. I imagine you are looking for black, but here are some ideas that include a few colors, as well.
POR15 Grey, Silver and Flat Black (brush on or spray with care). These flow out really nicely even if brushed. They stick like crazy to almost anything that is oil free (but don't get it any on your skin!) and are very tough.
However, all three will discolor over time when exposed to UV light, so are really most useful as base coats or in areas that will never be exposed to light. Top coatinig these can be difficult, POR also sells an intermediate primer that I haven't tried. I don't bother trying to clean up brushes, just use cheap single use and throw them away. I've had to re-sandblast some parts coated with POR15 and it's very hard to make a dent in it! I wish it were UV-proof! It would be the perfect undercarriage paint! I've had some trouble with uneven sheen with POR15 Flat Black. It also might be called low gloss, I'm not sure... it's not super flat, Duplicolor Low Gloss is flatter, and is prone to getting some shiney spots if applied in uneven thickness, would be best sprayed but good luck getting the sprayer cleaned up afterward. It does flow very nicely off a brush or sponge type applicator. At this point, I think I'd use this as a base coat, with Chassis Coat or similar sprayed over it.
POR 15 Chassis Coat. This stuck goes over POR15 pretty well, is semi-gloss, about the same as original Triumph chassis gloss, but seems a slightly greyer color to me (or maybe it's the fluourescent lighting in my garage). It is no where near as tough as POR15. I also brushed this on and it flows pretty well, but not as well as POR15.
Duplicolor Engine Paint - Gloss Black, Low Gloss Black and Clear Gloss. These go on nicely, in general. Low Gloss is a lot less shiney than original Triumph chassis, really is a flat black, but is the best at covering flaws in the part and is easily the most durable of all the "rattle can" paints I'm using. Gloss Black looks great if applied correctly. But, it runs and sags easily, is hard to get a nice, even coat with this paint. When it's even, it's very glossy. But, a second thin coat, if not timed perfectly, gets bumpy and ends up a lower gloss, rough area. I've found a more controllable and even shine using Low Gloss as a base coat, letting it dry completely, then top coating it with Clear Gloss.
Aervoe Engine Paint in Silver, Cast Iron Grey and Gloss Black. Silver is good and durable, a moderately low gloss, almost a bright aluminum look. It gets clumpy and can be difficult to spray in colder temps. I really like the Cast Iron Grey color, using it as an accent on my TR4 (brake calipers, drums, differential, various engine covers, etc.) It looks great with both black and brighter silver. It's a little prone to runs, I had to redo one part recently. It's durable when dry. Aervoe Gloss Black is not quite as glossy as Duplicolor, which can look almost "wet" or "plasticky".
Note, all engine paints are heat resistant to a point, generally unaffected by oil or grease, but can be damaged by brake fluid. They also dry quickly, to the touch in 10 minutes, relatively safe to reassemble overnight. But, if doing multiple coats the 2nd one needs to be reshot within an hour of the first, or you have to wait 72 hours, or lifting may occur.
I recently tried the new "Plastic Paint" from Krylon, specifically formulated for use on plastic parts. It goes on really nice and looks great, has a nice gloss, not overly shiney. We'll see how durable it is and if it really works on plastic parts. Limited color selection at local stores, though.
Eastwood Co. offers some specialized paints I'd like to try. One is Satin Finish Clear engine paint. There are times the Gloss Clear from Duplicolor looks too shiney, But, using it directly a rougher surface tones it down nicely, such as a cast aluminum part like a clutch slave cylinder. I expect to use the Duplicolor Clear Gloss on the OD and gearbox, too. They also have their own "Chassis Black" paint to brush on or in rattle cans. Also, they offer a black radiator paint that has extra pigmentation, gives thorough coverage with a thin coat of paint. I'm going to try it on some cameras, as well as radiators!
Cheers!
Alan