Check out Paul Gage (sp?) in Canada --great urathanes -- I have them for both the 250LM and the GTO's --and, yes I think the hubs(wheels) are the same.
We just ran a "tourist trophy" race with Fly GTO's, Alfas, Monogram Cobras, Jags etc. We modified the GTO's by using brass inserts for the front axles and tightening them up. Replacing the guide is also a good idea!!
Haven't worked on the 250LMs yet, but imagine the same ideas prevail.