Unless you are talking about Baltic Birch, I would suggest you find a more suitable handle material than plywood. Furniture grade or not, it will have voids within the veneers. Also, the veneers are most likely soft, low quality wood.
If you begin with 3/4 on each side of the tang you're making a good enough amount of extra work that is easily avoided by using thinner stock to begin with.
Just an opinion though. Best luck