x 3 with what has been described above.. Thats like sticking a square peg in a round hole. If you make it fit, something is gonna break. And How!!!!!
If you want to have some fun, destroke your 400 cid rotator with a 3.625 stroke crank using a 4.030 block bore. You have a selection of connecting rod sizes to use; a 5.7, 5.85 or 6.00 rod. This will vary with the disign of your piston.
If you use the 6.00 rod you can have the piston designed to have the wrist pin slightly dropped keeping it out of the lower ring grove. This positions the piston and the wrist pin in a better location for travel keeping excessive wear off the piston skirt.
All figures pending above, you will end up with a 387 cid. That puppy will be so much fun on the street and at the track.
You'll have the best of both worlds larger piston bore and rpm ramping with the smaller stroke..
That little motor will rev up like a rubber band toy, bring you into your desired power range much faster and keeping the power range up there through your shifting points. You'll shift through those gears like they were going out of style...
Depending on your car/chassis, suspension and weight, you may find you don't need as much ring gear in the readend as you might think, which will reduce wear and tear on your motor if you are using it for street crusing.
This may not be an option since you already have your rotator, but if you are able to mix up the combo, I would advise you to look into it....