350 hp no big deal, 318 heads aren't gonna do it, any 340/360/magnum heads will depending on the head cam need will vary something in the 220-225° range should do it with 600-750, air gap and headers and at least 9:1 cr. 318 or 360 should do it just the 318 gonna spin like 400-600 higher rpm to do it needing deeper gears and higher stall to get similar performance.
These are 360's a 318 will respond similar just at higher rpm.