I too have used International Paints Perfection 700 2 Pack Yacht Enamel. It does use isocyanates but I found that if you brush it in a well ventilated garage there is not a problem with fumes. It has a pot life of about 2 hours. The vapour concentration is much less when applied by brush than when sprayed as the solvent concentration is lower. I bought the paint from a Yacht Chandlers and used it on the chassis of my 1924 Alvis 22 years ago. The paint has good self levelling properties and can be rubbed down. The Black is a true black unlike some powder coating that tends to have a greyish sheen.
The Alvis has now travelled over 50000 miles since my rebuild and the paint is still good. It is quite flexible but if chipped corrosion can start underneath the paint. As in all painting good surface preparation is the key to a long lasting finish. The finish itself is dependant upon using good brushes.