that's not the only difference. The 256 engine have longer rods, so the pistons are shorter.
You can use 447 part inside your 256 engine, There are several ways to go about this. Replace all the 256 internals, crank, pistons, cam, cam chain, tensioner. Use your 256 head.
Rebuild your 256 crank fitting the 447 rods. This lets you keep the 256 cam, a bit hotter.
Use all the 447 parts but swap the 447 cam sprocket to the 256 cam.
The 256 cam had 36 teeth on the cam, 18 on the crank. the 447 was 34 and 17. different pitch chain too.
Many ways to do it. Some easier than others.
Leo