Hey mate, series 1 and 2 differences are as follows:
Series 1 have the blue instrument dials and silver badging of skyline on front quater panel, series 2 have grey instrument cluster and red/white GT badge.
Interior of series 1 has smooth dash and centre console while series 2 it is the orange peel look.
Under bonnet, the timing cover of series 2 dont have RB20 on timing cover, series 1 do. And series 1 are about 30kg lighter then series 2.
Not sure of anything else, apart from mild variation in front bar i think.