i'd do a 25neo + some form of 25 box (some ppl keep the 20 box but thats asking for trouble, plus you can sell the whole 20det and box as package to the s-chassis guys)
then
highflow stock turbo/hypergear's big turbo with stock front housing (looks stock and still runs an internal wastegate
or
cheapy NZ manifold + kando t67 + 40-50mm wastegate
one will keep a stock look, one won't look anything like it, both should get near your goals
then for the neo motor, get some id1000's (reportedly run really well and can still give you good economy but will give you ability to run e85)
z32
nistune the neo ecu (make sure you keep vct!!!)
personally, ill be running one of these when i eventually get round to it http://www.deatschwerks.com/dw300-fuel-pump-tech/
either turbo should get you up around the 300kw mark, maybe even 350kw on e85