Budget cylinder heads for a 318
Stock heads will get ya to the power level you want 300-325 hp,but you would be better off with aftermarket heads no point putting much money into stock heads. Plus you can get 300-325 hp with less cam or make more hp with similar cam you’d use with the stock heads. 9:1 Cr and a cam like xe262h or xe268h or similar with some gears and stall you’ll have a great streetable combo.