There'll always be dissension over the restore vs retromod question. Clearly, a real classic, like the Cobra or genuine Bugattis and the like deserve restoration, but I'd question whether any Austin falls into that category. I say that as a born and bred, dyed in the wool Austin fan.
The Sheerline is a survivor, but I've never thought that mere age grants much value other than curio. It's not as though they're as rare as hen's teeth either, there's one close to here doing duty as a wedding car, for example. It's pretty well original, but has a few improvements to keep it running.
If it were mine, I think I'd try to keep it close to original, but I have every respect for someone who rebuilds a modernised version. It should surely be a lot more usable in today's traffic than the original, and I don't think deserves the insults.
After all, it's not like a Masterpiece was being destroyed!