I picked up a second-hand P.C. What else do I need to buy to make the outfit work?

[Micrographia]

Always fun to get a good Ebay score . My 2 cents...

- a tux shirt is good but a wing collar isn't needed, though if you want one go for it. I have a marcella shirt with a turn down collar that gets used with PC or evening suit and a pleated front with a wing collar if I'm feeling particularly formal in a PC (not often).
- a self-tie black bow tie is best especially with a wing collar. I wouldn't wear a regular tie with a PC or a tux shirt full stop, or a 5 button waistcoat with a PC. Both look strange to me and I don't think the PC is cut for them. I'm with you on not being keen on the ruche cravat look.
- anything other than a silver metal cantle and fur or hair sporran looks odd to me with a PC, though I know opinions vary, especially with regards to hunting sporrans. In general I prefer not to wear something that is acceptable daywear as formal evening wear (aside from black brogues and coloured hose) and a hunting sporran looks like a fancy day sporran to me . I might wear a horsehair with my PC or Montrose if the event included dancing
- you don't need ghillie brogues. Your Oxfords will work well, though personally I'd keep an eye open for a pair of black Oxford brogues for day and evening wear double duty (also useful when you're not in Highland dress).
- solid coloured hose of decent quality will be fine.

As already noted, you'll be wanting a formal sgian. Other details could include shirt studs and cufflinks. I'm UK based so can't comment on US jacket sizing . In general though fits can vary with cut and maker so buying without trying it on will always be chancy.

Best regards, EEM.