When i built the motor, we did indeed use a ProX 03.6642 rod kit however we diddn't use the pin that came with the rod kit. As mick had previously advised, we also ordered an extra (generic) 06.2458 big end pin. There was an issue in the build up of the crank and it had to do with the thrust washers as the ProX rod was wider then the Suzuki unit. I will check with the "Guru" who built the engine and find out what he used for thrust washers.
If you are starting to think that this is not worth the effort, then consider that all of this, including the labor, was cheaper than a Suzuki rod kit, that wasnt avalible anyway.
FYI, the small end pin, bearing & piston were all off the shelf Woosner oversize PE units as per the book. I went for the Woosner as it was the only piston that came with the teflon coating standard.