It won't be the Belle anyhow, I believe it's a bodge up of BEL bodies stuck on CIG underframes with CIG bogies, motors and control gear. It won't look right and it won't sound right either (at least to me).
You are probably right, but, nevertheless, it will be wonderful to see it back on the main line in anything resembling its original form. Modern preservation has to adapt to the requirements imposed upon it with creative solutions, and the sheer effort to get the project to where it is should be praised. One could speculate that, if it had continued in service for several more years, might it have been re-bogied anyway to improve performance and track wear - it's possible.
Getting dispensation to run such stock on the main line will always need compromises but I think this project is going to provide a fascinating experience for travellers and is another 'stake in the ground' for the recognition of our railway's heritage and an interest from the general public which probably won't be far short of that in steam. Just getting rid of the yellow warning panel alone is a significant step (especially as it could legitimately have carried one).
As an aside, I wonder if the SEG's 4-COR (3142) could receive similar dispensation during its restoration - they would make a splendid pair for tours.