Sure wasn't me that suggested an adjustable reamer, especially not from HF. The ones I have are only marginally better than nothing at all, I honestly think I could cut a better bore with my pocket knife! Besides, I've never found a place where they were needed on a TR. All of the joints that I've had to ream have the clearance built into the pivot, so the reamer is a standard fractional size (eg 5/8 or 11/16). The only exception I can think of offhand is the aftermarket bronze valve guides, but you really need an oversize fixed (and piloted) reamer for those.
However, I've never done the rocker bushings. After I learned about Rocker Arm Specialists, there didn't seem to be any point.
My experience with the adjustable reamers is that if you set them for the right size (as measured across the blades), they just bind and don't cut at all. Then once you set them larger so they do cut, one or more of the blades will tip sideways in it's slot and gouge the bushing, so you wind up with an oversize hole that isn't even as round as it started. Fixed "chucking" reamers are cheap enough, especially after you ruin a few bushings with the adjustable ones.