How deep is your wallet ?
A roller bearing turbo will cut down lag a lot, as well as your finances!!
A T3 is more than capable of this power, use with a .48 housing, and a decent chip/tune.
If you really want to go a lot less lag the better way is to de shroud the inlet valve throats, NOT the ports which must be the same size as std.
I have a T34 and it boost from 1500rpm 142ft lb, but is 330 ft lb at 3000 rpm all the way till 6500rpm.
The best mod I ever had done for £275.
My old T3 boosted well with 150 lb ft at 2200rpm, 240lbft at 3000rpm and 270 at 4500.
This was stage one, where it later did 280 solid bhp.
If you are really concerened you could use anti lag ?
tabetha