Weird question: I see Reynolds crank his Indy bushings then grind the KP down. Its weird since I've never seen him do a smith or feeble, but it made me wonder if this would make the truck turn weird vs running the same total hardness, but with harder bushings that aren't smashed down.
Re angle grinding down the kingpin - I know he did that when he tried the Stage 4 Indy trucks as they did have kingpins that were taller (just like the 215s), but not so much for any other normal truck, even though thinking back I recall another post where someone did a very professional job of taking kingpins down for him, the comments or someone asking how much lower they were - a thread or two I think.
That said, I regularly do that with most of my trucks, especially the back truck, which I run a thread or so tighter than the front, usually with low top bushings as well, so I can really get a whole lot more clearance, sometimes more than I need, but I don't like feeling the kingpin hit on anything. Regular stock bushings I can take down a thread at the back once they wear in as well, so I will use a grinder so I never have kingpin sticking up over the nut.
As to how the trucks turn, as long as the bottom bushings are still as they should be, it is no different with lower tops or taking the kingpin down a bit, usually the top squashed down more than the bottom anyway.
Some of my trucks definitely have felt a bit more weird with the conical bushings I use if they have really squashed down a lot, still not even a full single mm, but yeah sometimes people like or prefer that turn and how they feel rather than having taller bottom bushings which mean the trucks will turn more like Ace, or Stage 4 Indy.
Also, I seem to recall people saying Reynolds did usually ride harder bushings, even had them put in for him before they sent them to him, but I don't know how accurate that is, or which colour they sent - maybe black ones?