ill tell you from experiece....1) they are cool pimp-a-licious, 2) ive made a prototype set, and 3) they are a MAJOR PITA to make....so dont hold your breath for me to make some...
Also some company in the Netherlands does make some for relaitively cheap.
A guy on G20.net got a buch for us from there, Scyzor is is tag name, here is the thread. There are some dimensions listed on the second page or so.
http://www.g20.net/forum/showthread.php?t=28228
Nissan is usually pretty good about keeping gage clusters relatively the same, I heard the 300zx rings would fit a P11 as well. Dont know about the B14, ***, my guess is they would work.
http://www.conceptzperformance.com/C..._Type=300&UID=