The bushing "stats" for stock ones are:
Length: 1.750"
ID: +.0008" to 0.0012" over the collar OD
OD: Varies a little because of arm distortions, so you must measure your existing arm before starting. The arms are often "coned" toward the outside by as much as 0.0020" (the 550 is the worst at this), so you may have to taper the bushing OD to fit it right.
If you use Oilite, make the interference fit 0.0004" to 0.0008". Any more than this will compress the metal on insertion, and you'll then have to hone the ID after installation. It can be done, just takes patience.
If you will grease more often than most, you can also use SAE660 bearing bronze, which turns easier and is harder. But, you MUST grease on the 3000 mile intervals with this, or it can wear the collar quite a bit.
If the collar's bearing surfaces are worn oval more than 0.0010", get (or make) a new collar. If the gouges in its surface comprise more than 93% of the surface area, you will need a new one or the bushing life will be short as the gouges tear up the bronze and grind the rest of it away.
After this "rush" dies down, I plan on getting some 650 collars made. Honda has quit them. I have done this with the 350F/400F already, since Honda quit those some years back, too. If they stop with the 750/500/550 collars, I'll start making those, too.
