Most of that gear will probably need to be custom made - eg. forged pistons, aftermarket rods, etc. What you'd need to do is get a sample (ie. pull your engine down) and send the part off the a workshop here and they can probably arrange it. I believe there is a company known as APEP (not 100% sure on the name) that does custom forgies... they would probably be able to put you onto someone who could do the custom rods up.
There's no real aftermarket for the 1GGTE here either as they were never sold here.. they're generally used for a swap into a relatively light (2200lbs) street car, which leaves most people happy with the basic mods like boost/exhaust/intercooler.
As for Japan you'll find they've no doubt moved onto bigger and better things by now. Great engine (I just bought one).. but always remember that being a trendsetter costs you a lot more and generally provides results that others vcan duplicate easily for a fraction of the cost... and then you're not only not original any more, you've also spent a lot of extra money to get there.