Humor me for a moment, if you will.
Regarding the tall(ish) kingpin height and the resulting "need" to increase clearance through modification: rather than plop in an inverted kingpin and dealing with the compromises they entail, why not take an angle grinder, or cutting wheel to knock 2 mm off of the OEM kingpin, in situ, and then use an ACE "low" top bushing, (or any other 10 mm, conical, top bush that is approximately 5 duro harder than whichever 14 mm, barrel, bottom bushing you happen to be running) effectively preserving the exact baseplate-to-yoke dimension, thus maintaining the same geometry. So long as your top bush is 10 mm and 5 duro harder than a barrel bottom, the turning characteristics will be almost identical with the capability to adjust for rider weight whilst still running loose adjustment.
More clearance, no compromise, exact same turn, plus adjustability.
Note: my hypothetical scenario uses lower stock bushings, rather than the cut-down method that Brimmo & others have mentioned, because, if you're really going to get into truck madness, you're going to want to insist on retaining factory width at both the top AND bottom of your bushings, requiring a steeper taper, rather than simply lopping off the bottom, resulting in less width/material at its new wide end. By using lower factory bushings of 10 mm height (or less), the rebound pressure is exerted from the turn's initiation, as the inner lip of the yoke is already in contact with the outer edge of the bushing, so compression begins right away.
Seems like those with the tools to do this would benefit from this method rather than fucking around with inverted kingpins, which may, or may not be too tall to permit tightening them down, if THAT's how you run 'em.
As for me, I like to run all of my trucks as designed, so as to "best" experience their intended geos. Further, the inverted pins come with a set of problems of their own. why trade one prob for another, rather than resolving it, ya' know?
My'pologies if this matter has been thoroughly discussed previously in this thread.
Just talkin' out my ass here.