On USA built cars in 66, the engines were typically painted prior to having accessories and their mounting brackets installed. Most of the brackets were blacked dipped (semi gloss), so your bracket is correct. Some of the AC compressor brackets and low pressure piping on the intake manifold were also often painted engine colour, but I've seen examples where they were black too. Throttle spring and trans linkage stuff were engine colour too. Interestingly, most Canadian engines in 66 were assembled with all their accessories installed, so power steering pump and brackets plus alternator/AC bracketry were most often engine colour. Alternators and AC compressors were not painted engine colour of course. Interestingly too, because they were assembled on a dedicated separate assembly sub-line, Canadian Police issue engines were not painted with accessories installed in my experience. FWIW, these are just my observations, and are only related to 66 model year. Nothing is cast in stone!