This is a question which our organisation has been considering quite a bit over the past few months.
To give a bit of background, the LTTG (London Transport Traction Group) was a group I originally set up in May on the basis that it appeared no organisation was going to be preserving one of the Class 483 (ex-1938 Tube Stock) trains currently running on the Isle of Wight, at least not in its entirety.
Therefore, the original plan was to approach the IoWSR and retain it in pretty much its current condition to reflect its use on the Isle of Wight and as potentially the only example of an IoW EMU to be preserved in IoW condition. We weren't thinking of long-term conservation however as our aim from the outset has been to run the unit. Upon approaching the IoWSR, however, we were told that they would be preserving one themselves, in Island condition and primarily as an exhibit in their Train Story museum at Havenstreet with an eye on being able to run in the future. To have one of these preserved on the Island in anything other than Island condition would be nonsensical. The unit that the IoWSR are getting is 483007 (recently named Jess Harper), which has just been overhauled and as such is in near-pristine condition and as such is, and will continue, to be a perfect representative of the fleet in preservation.
We then approached the Epping Ongar Railway. As the 483s are, at their core, still 1938 Tube Stock they are also appropriate for the EOR with its history as part of the London Underground from 1948 to 1994. For a period in the late-1950s, a 1938 stock set ran on the branch alongside two 1935 stock sets. With the IoWSR preserving one of the units in pristine Island Line condition, and with the EOR having no relationship with Island Line we feel that it's most appropriate for our unit to at least roughly represent a unit in London Transport condition. Although we don't plan to make any substantial changes to 483006 to achieve this, we are planning to do such things as a repaint into 1950s LT livery, re-trim the seats in period LT moquette and make minor cosmetic adjustments to reflect this - Nothing which couldn't be un-done, however. The most substantial difference is that as we intend to run the unit using its traction motors we will also need to make provision for batteries.
I think my point is that were our unit to end up being the sole surviving example of a Class 483, we would be preserving it in its current condition and making as few changes as possible to enable it to run. As it stands, we are taking it somewhere where it has a different story to tell and where that condition would be of little relevance when telling that story. 483007 will be telling the story of Island Electrics in the most appropriate environment possible, and as the unit in the best condition it is the best representative for this role.