I’ve found a ’75 Grumman AA-1B whose owner, saying they were uncomfortable, replaced the original seatbelts/shoulder harnesses with lap belts only. I seemed to recall that if shoulder harnesses were installed they were required equipment and couldn’t simply be removed. What’s the consensus (and reference, if known) about this action?

Part two would be to ask if there are effective and comfortable after-market restraints available for the AA-1 series?