73 318 will J heads work???

From what I understand J or X heads have to big of a combustion chamber for a 318 and it is really hard to get the compression up unless you mill them a lot. Which causes other problems and is not usually recommended. Unless you are building the motor up and are redoing the pistons and rotating assembly with maybe a set of dome pistons it is best to go with a set of heads with smaller chambers like 302's.