Converting a tweed sport coat to a Braemar jacket

[Bugbear]

One (dumb) question on jacket.

I see those jackets in grey and black colors. Are other colors not acceptable? There is a jacket (Harris Tweed) in brown-like color which I don't use for some time. The only issue I see (as total ignorant on this field) is, to what tartans this jacket could be used not to clash.

The brown tweed should be just fine for a daywear jacket.

I would avoid wearing it with tartans that have a large amount of black and/or gray.

It would probably look great with some kind of horn or horn-like buttons. Good luck.