Nice looking brakes! It took me about 3-4 hours for front bbk/ss line install, but I was not trying to rush at all and I had a couple of beers. You could definitely do the whole 4 corner setup in that time if you were more concerned about time. It isn't a difficult install really. Use a level or something to prop the brake pedal half down to minimize fluid leakage during the time when the line is not connected.
I don't really get the thermal capacity argument by some people ITT. Yeah, it isn't an insane difference going 355 to 380. But I don't think anyone on this forum could feel the few pounds extra sprung weight. So it is really just a wheel issue, and many 18's fit ST 380. Obviously OP agreed since you got the 380!