That last site looks like it would have the better colors, but I am attracted to everything but the RED, which is what I am stuck accenting with again. My red is very specific though. I think a nice crimson would look great with your theme.
I would worry about re-threading though, because the ends are sewn in a specific way I think that would lend the strength needed in a collision. Maybe I am wrong. It looks like the site sells the replacements as well. Dang.. this makes ME want some nice RICE RED seatbelts lol. Only I call it RS red.
You should do it.