Terry, I don't think an inch would be very noticeable, particularly if they were machined or ground to match the profile of the end of the bracket and then chromed. If they're chromed and shaped accordingly, I would think they'd just look like part of the original bracket when mounted up, only a "beefier" version. They can get away with the black on the front ones since they're down so low on the bike, but I'm thinking chrome would be better for the passenger brackets because they're more readily visible.
As far as the diameter of the hole, a powdercoater could keep material out of there no problem, but don't think the same is possible with chrome. You would probably want them oversized a bit to have them chromed, so the bolt still slides through. Shouldn't need much, though. Sorry, "a bit" and "much" is not too scientific, is it?
Speaking of bolts, are these allen head bolts available in a 1" longer size?
Tried calling a couple times tonight but got voicemail. I'll probably try you again the night I'm out by the bike to make sure I'm doing the measuring right.