If I had to pick between those two I would go for the Marlin. But with that much cash to spend I would try to find an older gun like your son has.
I like the new Marlins but the laminated stock and thick wood on the forend doesn't make me happy. I do like the ballard rifling and the 1/12 twist of the new guns. I wish it would occur to Marlin to put that same barrel on the blued models.
Some people think an English Bulldog looks great... many more people can't tell one end from the other, even by smell.
A village in Kenya called. They want their idiot back.