A very simple and effective solution to this problem...

Create a sleeve out of 4130 steel or similar, with a 70mil wall+/-,
make the length of the sleeve such that it is a snug fit between the
tabs on the nose gear strut. Now you can elimiate the castle nut and
cotter pin in favor a a lock nut tightened to proper torque. With
bolt/nut tightened, it will no longer be possible to elongate the tab
holes.

You will need to enlarge the bolt hole on the nose gear link to
accomodate the sleeve you've just made but there is enough meat at the
link end so that this is not an issue.

The chances are that the nose gear link will not naturally center itself
on the sleeve between the two tabs due to varying construction
techniques so you will want to measure and adequately shim either side
to remove any side to side movement.

This solution will undercut Rob's $50.00 threshold by about $49.80 not
including about 30 minutes of your time.

Angier Ames