its 4 cubic inch ... while yes there are some advantages to boring the motor it is just as easy to hit 900 hp with a std bore motor.

^ Like he said earlier, I would never trouble myself to bore a 12V unless it needed machine work in the bores for some reason already.
Making the power is easy. Holding it together with that power is more relevant, if only slightly.

Makes sense. Thanks guys

If a bigger bore is better how can I use my 6.7 short block with a 5.9 head?

You can't.