Compression reading alone won't tell you that, and $395 is wayyy to cheap to have a set of heads rebuilt. $395 each is probably within reason. But you need a leakdown test to determin, valves or rings, or head gasket. Comp test tells you there is a problem, leakdown tells you where it is
A truck 302 out of a 90's F series is in the realm of a $300 motor running. It will either be roller cam ready or have a roller cam ( 1993 and later. I think. don't quote me on that ). That only matters for the distributor because you would need to swap distributor gears on your marine distributor if it were a roller cam.. You just need to put marine core plugs and head gaskets into it and possibly change front cover and oil pan depending, since Ford used a number of different things. You can check the compression on a motor even before you buy it