I may be showing my age here but back in the 70's I was one of the first guys in my area using Nitrous, I found that by building a simple water injection system (using winsheild washer fluid instead of water) I was able to increase the Nitrous charge wthout detonation, this should work with forced induction as well.
The water injection system was a simple plate under the carb with a tube to the windsheild washer tank that used the engines vacuum to get the water into the manifold.
Maybe worth a try.