OMC 175 Carbed Compression Increase

[Tarponhead]

Engine in question: J175VXSIF 2001 Johnson 175 Ocean Pro
I have read several posts on guys doing builds and being advised to switch heads to another MY or part number as a simple way to increase compression ratio. I am interested in exploring a similar mod for the above stated engine. I want to be able to continue to use nonethanol pump gas rated at 89-90 octane, and I do not want to increase the comp so much as to adversly affect the engine life in a big way. (Read: I dont want a grenade on my hands). With that said, I am aware that most engines can withstand a bump in the compression ratio with little or no adverse effect.
Are there any such bolt on mods for this engine?

Thanks for the help.
Tom

[Merc 2.5]

Without a 20lb increase and rejetting you probably won't never b able tell u did anything,now if u bump it up 20lb and and rejet, it's a feel it n the seat difference jmo