ls powerplant will be stronger and cheaper. Build a jy 5.3 with rod bolts and a cam with some good valvetrain and let it eat.
I am not sure what your plans were as far as a trans but with boost I assume you were going with an aod or c4. Just do a 5.3 and a th400
I know I have built a turbo ls coupe on paper more times than I care to admit, including a donor car I know I could build a sub 10sec coupe for less than 11,000 complete