In regards to a headrest not mounted to the back of the seat: Don’t make the headrest too solid, as that can be problematic in a rearward collision such as a backwards spin into a solid obstacle. You need some give.
After looking at my options I think I can come up with a solution by mounting the headrest directly to the underside/back of the seat similar to how the original seat is done but without the excessive fiberglass.
Greg the reason for swapping out the old seat is its too wide for me. The new rpm seat I bought doesn’t have a head rest but fits me nicely! Trying to see how everyone else adapts a headrest either to the seat, body, or chassis.