As all the others haver said dreesing down a PC does not work, however with the right Argyll you can go almost anywhere provided you have the correct accessories. If you are looking for a vendor on this side of the pond you could look at the Scottish Tartan Museum or USAKilts, if you were inclined to order from Canada you could look at Cairngorm Scottish Imports they are starting a sale on Monday November 5, on ex rental merchendise.
Take a look at Arlen's post about his wedding outfit, and through the formal style thread and you will see examples of the Argyll dressed up to formal standards.
As for the PC jacket with an Argyll waistcoat, this seems to be a more modern take on things, let me just say that I am not a fan of the look, and would advise you to go one way or the other.