Im also looking at interior retrim options for my build.
I think IMO the dash always has to be black, i think any other colour is a bit in your face although it can look great sometimes.
The dash etc are very hard pieces to do, make sure you see examples from which ever company you choose, i'd hate to see wrinkles and stretch areas in something i'd just paid a lot of cash for.
I'd ideally be doing the same, Roofliner, Seats and perhaps the dash in future. Don't forget once you start doing the dash and A pillars, you'd have to do the rest otherwise just stopping at the A pillars could look silly?
Red seats always look great in a black car. Marc on here has one, the super low car with red leather interior, can't remember the username perhaps MarcAb10 or somthing