Dominator mudguards

You can drill the guards with a decent sharp drill slightly oversize.  I tend to use Cobalt drills most of the time now, but they are quite brittle.  VERY hard-wearing otherwise - best from Screwfix or  Toolstation.  Many advertised on eBay are not Cobalt.  Always tape the holes before drilling to  protect the chrome.  A decent anti-rust then silver metal paint should protect the holes and chrome afterwards.  If you're really keen you could coat them with plastic too.  As used in fibreglass repairs.

Getting the radius right on repro mudguards is a black art and doesn't seem to be consistent - even with our trusted and well-known metal-bashers!  Mine aren't easily accessible, but are for my Wideline so not relevant to your width problem.

Drilling them to suit your bike is likely to be better than having them pre-drilled by the Indian makers anyway.  Only time will tell if the plating is good quality triple-plate.  (Copper-nickel-chrome).  OR you could spray them with a clear-coat after drilling, like you must use on metallic paint (or anything else for protection).

They are handmade, and as such will be variable. I imagine that back in the day there would have been a set of forks hung in the tin-bashing shop to try them on until they fitted right, and they would not have been plated or painted until they did, the same with exhaust pipes, I have had some that were shocking, even though the makers made very grandiose claims of quality and fit.

The width remained the same but the indents in the sides of the front mudguards were deeper for the pre 1964 forks. I have a previously used later one my 1963, and managed to make it fit after some hard work with a big vice and hardwood blocks for a press. Not ideal.

Doesn't matter who does the chroming, the chrome is porous and the nickel provides the barrier to the water trying to get to the steel. So if your nickel is lacking then wax that chrome to fill the pores on a regular basis and pray that the bond between the chrome and the layer below is good.  

I bought a rear guard having finally given up thoughts of restoring my old rotted one on a '61 99SS. Which had been marmalised and welded a lot in antiquity, then stove enamelled cream over the original chrome (or what was left of it).

The quality of the chrome on the new one is good, but they completely ignored the careful drawing I sent them setting out the holes. So a lot were missing, and the cobalt drills had to come out.

I just greased the new holes )-;