i may not know to much about the the turbo b20 but i do no that if you put a vtec head(b16) on you will most likely only get a year out of it dependiong on how hard you beat on it.
my ls vtec blew the head in about a month and a half, too much compression pulled the studs out of the block on the number 4 cylinder.
b20 is also meant to run at low rpms, the vrtec will put extra strain on te motor that you dont really need.
just build the internals and put a bigger turbo or put some spray to it