Get a set of Vortec heads from Scoggins-Dickey, check Ebay for a Vortec intake, and change the cam. Make sure the cam lift is in line with the max lift for the valvesprings. You should be able to do that for a grand and get you close to 350hp. Remember, your best power will come from well matched parts rather than from the biggest of everything. Research what performance parts work well together.