good job keeping the L flat hood...i've had that idea knocking around in my head for quite some time...too bad someone beat me to it.
from what i found, an air-to-water intercooler from a legacy turbo should work just fine with the stock hood. i've seen them go in the classifieds in really nice shape for $200-250. of course there is always the front mount, but then you're talking serious $$$.
good luck!! let us know how it goes. if you need a FWD L donor car, i'll give you mine...provided i can use your WRX during the week, and get the L on weekends...