I'm assuming that's a standard 383 OEM forging? Pretty impressive!

We know that short strokes and long rods put a lot less stress on the block, I guess that is amply demonstrated here!

For comparison....In terms of piston speed (5512 feet per minute) this would equate to only about 7800 RPM in a 4.25" stroke motor.

At 409 cubes I'd still rather have a W9 headed R3 48 degree block and probably make the same power but it is still very impressive for a stock 400 block stock 383 stroke crank motor.