the three in the back bear some resemblence to the Hitachi version of SUs that came on early 240Z's. I don't recall them being so crowded with stuff near the piston chamber. They did have a distinctive flat top unlike the rounded top on SUs.
take a look at this link to ztheraphy.com
https://images.google.com/imgres?imgurl=h...l%3Den%26sa%3DN
What are the 2 single barrels?