right my opinion, and these are the cars i know inside and out, for that budget id be buying standard and tuning it your way, as thats a stack of cash and if you were thinking gtr you would get a clean 32 gtr for the top end of your budget. also id consider bringing one in from over here in ireland as youll get a car for alot less the way they are at the moment.
dazza's car on so.com is a clean car, but the interior is a little marmite tbh.
http://www.pistonheads.com/classifieds/used-cars/nissan/skyline-r33/stunning-nissan-skyline/1407318 (thats a nice one and what id be getting out of that list but its not worth that money if you ask me)
have a good look through the for sale section on so.com and youll get something tasty for the right money. also id take my time looking at them and get the one you really want. its a buyers market so dont be afraid to lowball them too.
moff who i believe is on here too has a clean spec 1 for 2k bonnet and headlight swap gives you the spec 2 look if you prefer that for roughly 300 quid too.. then tart it up how you like.