Mate your LS head to a b20 block after you have street stripped ported/polished. Upgrade the crankshaft, rods & pistons to bump up the compression to 2.0 which is what your bottom end will be. Add some crower cams and you'll have the all motor torque your looking for. Or you can go forced induction, both are costly and best would be to turbo the b20 setup but that will definitely set you back. It is always better to force a "built motor" as opposed to stock. Hope this helps.