Is One Better Than The Other & Why?

If you stick the piston out of the block like Chrysler said to do 55 plus years ago it doesn’t make a pinch of **** difference.

In fact, I can argue that the original SBM chamber is better than 90% of the **** that gets palmed off as the latest, greatest thing.

The MOST timing you should need on a SBM is 36, and that engine is probably low on compression and over cammed.

A lot of the guys out there today claiming their chambers will run at 34 (or less) run a far hotter plug than they should.
Hotter sparkplugs CAN burn more fuel (or burn fuel better so more can be added), so if done right will make more power...within reason.