Red, or may also be termed as scarlet, tartan red, or brick red, is a superb choice for a waistcoat to be worn with the kilt, however, I tend to restrict this colour for evening or formal occasions. I currently own a 3-button waistcoat made of scarlet worsted wool, to be worn with my regulation doublet for the evening. With regards to the evening, tartan hose in the Clan Dhai sett would be most appropriate, just as cath dath, or red and white/red and black diced hose would work just as well. For day wear, solid red hose perhaps with some sort of dicing on the turnover would look quite smart. I suggest the Bowmore hose from The House of Cheviot, in brick red. Cheers!