Are the wheels solid metal
Yes
how are they attached to the axles
looks like a knurled section under the insulating bush that separates wheel and axle
and what diameter are the journal ends?
4mm (well, the one that I've measured. They are a good fit in the roller bearings)
I guess I'm really asking how easy it might be to turn the flanges down....
Definitely do-able, you'll be needing to turn the width down to suit as well but I'll let you pull your wheels off, mine are happy in their current location
And have you worked out how easy it will be to remove the "plinth"?
Not yet, but I have got as far as stripping it down to its main assemblies this evening - it only took 10 minutes but I've been delayed by stripping and cleaning an axle pump. A decent phillips screwdriver gets the body to pieces, it uses the same screws for all the bits I've taken off so far (bogies excepted).
These things are absolutely brilliant as far as I'm concerned
They run fantastically well, they have genuine Kadee couplers that stretch out on curves and pull together on the straights to keep the rubber gangways in contact and they lend themselves to a bit of individualisation. I need to glue in a loose interior panel (see top left), find out what colour the seats and partitions / corridor woodwork should be and slap some paint on, slim down the roof ribs and get some matt paint over that. A spot of light weathering will bring out some detail and they'll do for this season at least.
I think some careful fitting, rather than mass assembly, will see a better fit along the plinth - in the short term I'm tempted just to add some body colour to that edge whilst the coach proves its durability. I've not looked at it properly, but I suspect that you could probably extend the body sides with some plasticard strip and maybe trim the plinth off the chassis although I acknowledge that doesn't leave much support for the body on the chassis, it will rely solely on the small tabs that hold the screws.
Lots of fun ahead then
Steve