Different bottom metal and hole spacing than Pre '64. They use the post '64 layout with the exception that they have done away with the 3rd middle screw. All bottom metal is now post '64 one piece. Long or short...
The new FN long actions still have the hole for the middle screw...mine is a 30-06, the factory bottom metal doesn't use the middle hole, but the hole is there in the action...and threaded.
The only thing that Winchester/FN lost to Remington is the number of aftermarket parts available, and that is good for Remington because they certainly need it. The M-70 action is superior to the 700 in every meaningful way. I wont even consider even a expensive custom copy of a 700 over the M-70. For me, the only available improvement is moving up to an AI.