I'm honestly more partial to the 180SX as well.
In terms of power/reliablity, low 12s shouldn't be asking too much. I'm estimating 350wrhp, My goal is around 330-350wrhp. From what I've been reading about the CA18DET, it should hold that pretty well.
Of course, I'm going to have the engine rebuilt, the seals redone, metal head gasket, new cams, new head bolts, flywheel, clutch etc, tuning. This isn't gonna be done out of nowhere.
In terms of suspension, I've got quite a comprehensive list of what I want
AS long as it rides like my Spec V, I won't have any complaints, the ride sucks already, and I'm used to it
In terms of streetability, I think it would work. I'm planning to have a PowerFC and a Apexi 3 stage boost controller, so "winter mode" "summer mode" "track mode"
Winter mode will consist of no or little boost, which with steelies and winter tires, will get me through winter fine.
Now I also plan to have a system, so that'll probally make it a mid 12 second car, but it should be okay.
In my cars, the "fast" cars run low 12s, to 10s, and they're streetable daily drivers. Hell there's even a Supercharged Bigblock V8 Camaro that even goes through winter, and it's running 11s
But I'd like to hear what makes it impossible? But maybe that should be another topic, which I will post later tonight.