You can play 3NT as "reverse Namyats", showing a Namyats hand in either major. The response structure is: 4♣: Artificial slam try. 4♦: Asks opener to bid their suit. 4♥/♠: Pass/correct, slam try if opener holds the other major. After 4♣, opener bids (my idea, but surely there are several possibilities) 4♦: hearts, no side ace 4♥: spades, no side ace 4♠: hearts, a minor ace (4NT asks which) 4NT: hearts, spade ace 5♣/♦/♥: spades, this ace This structure makes responder have more control over who declares. Responder cannot choose to declare if they do not know opener's major; but then they are unlikely to hold a tenace. Another nice feature is that you can play four of a minor as a good old natural preempt.
