Jason, The groove does not tell anything about the lifters, only how the oiling setup should be.
The way I would check to see if it has hydraulic lifters is to turn down the adjuster on any valve that is closed a few turns and let it sit for a hour. Then measure how far that push rod is sticking out of the head. Then back the adjuster off and see if the push rod comes up out of the head any. If it is a hyd it will come up, if solid it will stay the same.
