I would not be inclined to change a stock original in good condition. I would be more likely to keep it as-is or sell it to another collector. Especially if it had significant value.

But I could see my way clear to make changes to one that was in bad shape or that had been previously modified by someone else - e.g., I would feel free to drill and tap and mount a scope on it, modify or replace the stock, re-barrel, etc.