Will this work ????

I can help here.
Recently been through it all myself.
My 440 is 30 over and the slugs were 100thou down the bore at tdc.The heads were 906s with 40thou gaskets.I cc'd and measured everthing and came up with 8.4:1

I replaced the 906s with 915s (measured them again)and used tin shim head gaskets and came up with 9.3:1

How does this translate to actul improvement?
I picked up 0.25 seconds on the eighth mile straight of.No other changes.
Haven't had it on the quarter since fitting the 915s but it looks promising.