How much more hp will i get with built camel back heads on my 350 chevy?

I have a real built sbc 350 i have 305 heads on it now im getting camel backs built for it, a matched high revving thumping cam and roller rocker kit. How much hp will i gain. I have 4:11 rear end and were getting a 4 speed muncie. How much hp will i gain and how much quicker will it be?