Using a thin gasket is a horrible way of increasing compression.

You could easily reach your goal going FI. And if you do decide to go FI, use the GSR motor. Theres people on this board runnining turbokits with just under 290 WHP, on stock internals. A Properly tuned engine can be just as reliable as OEM. With forged pistons and rods, you could make 400whp.

You will spend alot more trying to acomplish your goal NA, although it is possible. Budget around $8K, including the cost of the B18C5.