Can you post a picture to give us an idea what it looks like?
I don't know anything about the kit, but my guess is that the /Park means that it's a Parker style twist and maybe 8mm. To figure out drill size, I'd use my calipers on the tubes and decide from there.
As for bushings, I'd use calipers to measure the components. Then you can choose from among bushings you have that fit in the tubes, or turn between centers.
If you come back with the measurements, I'm sure we can help you find suitable bushings from the library charts and instructions for assembly.
No calipers? You won't regret making that your next purchase.