Being in the US I have an abundance of US size hardware but everything on thingiverse is in metric (which is honestly superior). Since i already have US size hardware and the ability to modify the parts I print it is a lot cheaper to make new ones that fit my hardware than to buy new nuts and bolts.
Anyway, The only modification to this part is that it will take a #6 nut and bolt.
To secure the bearing in the holder you just poke some wire though and bend the ends so it won't come out. Make sure it won't touch the smooth rod.
UPDATE: 4/24/2018 These are working great for me at 103.5%. I have not changed the model so you can adjust the size as you need to. I'm calling this thing complete for now.
UPDATE: 4/17/2018 This is still a work in progress, but I had to scale the model up by 3.5% (103.5% total size) in order to get my igus bushings in. I then used an 8mm wide scrap from some . 08 mm height brim underneath as a shim. The idea here was to create a "floating" mount that will allow small amounts of movement in the bushing but still track accurately.