Hi Bill,
First off, great restoration, I have been following your progress for years. As far as whether a total rebuild is more correct then a frame up restoration it really depends on what you have to work with. Using the same practices and materials that would have been used when the artifact was in service is the correct way to go.
When the Northwest Railway Museum began the restoration of standard gauge White River Lumber Co. Caboose #001 we had little choice but to do a frame up restoration. Years of damp weather had taken their toll. But even with that a number of pieces were able to be reused. At this time the frame is completed and as soon as our Conservation & Restoration Center has the trackage finished the project will continue. To see what our new restoration facilities look like go to:
[trainmuseum.org]
See the link below for the work done on the caboose.
Richard Wilkens