Exactly right- nitro has 25% of the energy content as gasoline, but you can burn 8.7 times more nitro with the same amount of oxygen. This means you have to get the carb to deliver 4 time more fuel than gasoline to equal gasoline. If you want more power, you have to go up from there.
Point of fact- if you increase the fuel delivery in you engine enough to run on nitro- it will not run on gasoline. If you do not increase the fuel delivery, ay best, power will not increase.