Cylinder head decision for 318

Personally, I wouldn’t spend the money on putting “big” cylinder heads on a low CR 318.

Have the current stock heads refurbished, mild bowl and pinch work, upgrade the spring/seal package...... install a suitable cam..... and run it.

Use the $$$ that was going to be spent buying the “big” heads towards buying a suitable 360 core instead....... for when you actually want to make some power.