I would counsel caution in reproofing nice old guns where there is no need.
In the course of my restorations I almost invariable reproof and in the last year or two have gone from a very occasional failure (about one per year or one in twenty) to the majority.
Having said that, they nearly all pass proof eventually but now I presume to have to knock down bulged chokes, 'lift' invisible bulges, strike off 'unevenness' in original damascus and generally deal with a proof house that seems to have lost the plot!
The incidence of bulged chokes is getting beyond a joke yet my barrel specialist who has been doing proof work for decades had NEVER had a proof induced bulged choke until the last year or so.
Basicly I have no choice but to submit my guns for reproof but I wouldn't recommend anyone else to do so unless really necessary.
Even freshly sleeved guns are often failing proof on first attempt!
