Every car is different so you can't put an exact figure on power output, plus you have so many other variants to consider, ambient temp, pressure, humidity,
You may benefit a little more peak HP with a 3'12 as the intake temps will be a lot lower but lose out in torque mid range.
I ran the 3'33 on my 350 & accompanied with the cosworth intake got 430rwhp but the mid range torque was a lot less than those running the smaller pulleys.
Get some dyno printouts up so we can compare to others