Another nifty thing to do to heads is to shave them in order to place near the plug of the piston. JP Racing does this on their chamber heads (so everyone is warned about exchanging the chamber heads of a JP for a stock Nova one).

I'm doing them on some of mine engines, but going at a very small pace (0.1mm each step). For this thing a lathe is mandatory in order to keep the combustion chamber squared on the sleeve.

EDIT: You can see another use of the scooping on the link I've put. This time done on the pistons dome.

http://www.popularhotrodding.com/eng...05/0604em_emc/