[blykins]

FE stroker kits are very common. You might wanna give Keith Craft a call. He builds 550hp stroked 390's all the time.

You could take that block, clean it up with a .030" bore...and use a 4.125" or a 4.25" stroke crank. That would be 431 or 444ci.

Add some Stage 2 Edelbrock heads, a hydraulic roller cam, and you'd have some good streetable, reliable, horsepower. And you'd still be period correct.