OS Giken are still in business & turning out clutches as well as the rb30 kit so hopefully if I can get hold of the part number I may get somewhere.. ive emailed os Giken in the USA & in Japan but haven’t heard anything back yet and I’m not sure I will do. If I know the part number I need it makes life a little easier and I may be able to source one through nengun or similar.
As for your second question, I guess it depends - off the shelf they’re like $13k US but I’ve heard significant discounts are available over retail and nobody really pays full price… dunno how true that is, but it’s really not worth that much tbh when you consider the new price of a regular RB28 kit. I paid $4k US for mine, but not in perfect condition and with pieces missing. I had to have the crank reground + new bearings and also the ****head that stripped the engine did not know that the cam pulleys & flywheel were specific to the kit. So now some other poor guys probably have cam pulleys and a flywheel that are basically paperweights without the RB30 crank to go with lol. I just had a new crank pulley machined from 4340 with the same number of teeth as the stock so now I can just use cam pulleys from whoever (the OS Giken crank pulley is 1 tooth less than OE, or one tooth more that OE if you order the kit that is compatible with HKS Valcon, lol…)