Other than having a little more compression, the 848 head doesn't offer any real improvement over the original head. You can equal the later head's compression ratio by milling .090" off the original head and recessing the intake valves the same distance. That's important to shroud the edges of the valves from the flame front that travels across the head every time a spark plug fires. Hotrodders were doing that in the late 1950's to avoid having to buy a new 848 head. It still works.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!