Engine paint colouring for 250/275

Hi everybody, we are trying to find a suitable engine paint for our 250 and 275 engines to achieve continuity and authenticity when completing engine rebuilds. An esteemed colleague advised harley davidson block paint. BUT my main question is....was it of enamel makeup? Any advice on colour, type or even application would be appreciated. Also how thick was the application of the block sealant?



Thanks in advance.