My girlfriend bought an R33 96 series 2 NA Auto about 6 months ago - she paid 18k for it, but it is the cleanest original skyline i have ever seen (has aftermarket exuast thats it)
Even the things like scratches/marks on the interior you mention hers doesn't have...
so hers is a series 2, done about 70,000ks, immac cond, yours is series 1, same k's, not quite immac condition and i think my gf paid too much for hers... you should be happy if you get 15k for yours