My First car was a 1966 Mk 1 cortina 220 two door..... with a 220 hp Pinto/1600 twin cam hybrid in it, twin webbers, Spax adj. race sus, Capri V6GT brakes, superlights etc, Was built along the mines of my dads Appendix J racecar (66MK1 Lotus), and Im glad that was my first car... as I learnt NOT what to do.
My dad and me built it over 6 months, he tought me how to drive in it..... and I stacked it the first night out on my P's LOL.
From experience.... get a R31/KE70/AE86 or something like that, cheap, still can be modded, and still capable of being driven hard, learn how to handle it, then step up to something more powerful, or continue to mod that. (I have a Rb20DET 31, be making 250kw's when the TD06 and injectors go in and tuned)
There's a S3 RB30 5 speed 31 for sale on the 31 skyline club for $1500, add $2500 for full S13/R32 coilover and brake conversion/swaybars/panhard/bushes/tower bar/castor arms etc, get some decent wheels for it, Extractors and exhaust and clutch, spooled diff and a few other odds and ends...
Be a very competent car in the hills, can go out skidding, yet still drive it to work every day, not get hassled by the 5-0, cheap insurance, parts are plentiful and cheap, and can drop a turbo driveline with VERY minimal hassle when you want some more grunt.