Hmmmm.....I am inclined to say Heads or if not heads maybe cam?

Who built the engine for you? Seems like an odd combination of parts to me, but I could be wrong. Just does not strike me as a well thought out or matched set.

Please don't take offense I am not bombing you just offering my thoughts. I takes alot more than just putting in a bigger cam and a shot of nitrous to make an engine work properly.

is that cam designed for the compression you are running?

What exactly are the heads? a 383 needs air flow.

Many questions,but something is obviously not working right if you are only running 16's with a 383 and 100 shot of nitrous.

I am sure there are alot more knowledgable guys here to help you out.

good luck,
Dan