AFAIK the PI block does not carry any special markings. The PI block is cast with stronger thicker webbings very much like the CJ block. I havenīt compared them side by side but I couldnīt see any differences. The PI also carries the bigger stronger rods like the CJ. I like to think of the PI as the predecessor to the CJ - just build with the Lo-Po heads of the 390.
One key element is the PI aluminium intake much lighter than the cast iron anchor of the CJs and every bit as powerful.
Combine the PI short block & intake with Edelbrock heads and a healthy cam and youīll end up with one hell of a powerhouse.
Mike (Germany)
68 GT500
Not a cobra but same heart