What head was originally on the engine? The 906s will work, but I recommend 452s because they have hardened seats, flow the same, and are usually cheaper. However, in either case they not be the correct head that the engine was designed for and the compression level might change. Look at the flat stamping pad on the front of the engine (above the timing cover) and that will tell the year of the 440. You can also read the casting date on the side of the block, but usually the exhaust is in the way.