There was also a 150E 16-valve version of the 3K / 4K engines. These 16 valve heads were the forerunners of today's 4AG, 3SG, 7MG, and 2JZG engines. These were race only non-production heads, with heavily modified blocks
Non production - hard to find
heavily modified block - dunno what mods
3K/4K - Not 5K