Welcome to the list, you have a fine boat.
The top section of the cubby hole where the winches are mounted is all cored with 0.5" plywood, so the winches can be mounted anywhere. But be sure to fill the old holes with epoxy filler to seal the plywood. For maximum strength in the new fittings, you could get a machine shop to make up backing plates for the winches to mount under the plywood. In US prices, they would together cost less than $50, and would give the maximum possible strength to the winch mount.
Gareth
Freyja E35 #241 1972