Education needed on copper head gaskets. I have a 468 Bullit roller motor in a Mantra Performer. Eagle crank/rods. J/E pistons. Dart Pro 1 aluminum heads. Being a lake boat will be its only purpose. This is my first engine to own with copper head gaskets. Don`t know much of its history except that an idiot with more money than brains previously owned it. He didn`t run a dipstick so i`m pulling the oil pan to check the bearings etc. The dipstick hole is plugged with silicone. I can see on a tab sticking into the lifter valley that says 4.370 and .040 . Heres my questions; does running a copper gasket automaticly mean that it would have to been o`ringed? Dependable without water getting into the oil? I don`t know whether to go ahead and try it or not. I can see where a small amount of orange silicone has squished out all around the head. I believe the block has already been decked by looking at the right front of block where the number should be. How deep are o`ring grooves usually cut? If only the heads are ringed maybe i could have them shaved. I`m thinking i`d be safer with fel-pro 1017 gaskets. Or would i? Thanks in advance for any info.