Another "recommend a cylinder head?" thread!
You are correct in your guess that a closed chamber head will improve quench, it will also most likely raise your compression ratio even more.
What pistons do you have in the engine now? What is your deck height? What is your cam shaft? Where is it installed, and what is your cranking compression? What is your ignition curve?
These are all things that influence detonation.
You could bolt down an aluminum head.