[Formulajones]

The 455 has a 4.210 crank factory. The aftermarket makes 4.250 cranks that drop right in to either a large main 455 or a small main 400. The 400 just needs some simple clearance surgery on the block itself to clear a couple of counter weights.
Larger stroke cranks are also available.

It's been a popular mod ever since the aftermarket has been making them. Especially since 400 blocks have always been more plentiful.