Modifying the cylinder head on an A-series is fairly straightforward and well documented, since people have been doing it for more than 60 years. I happened to have a copy of David Vizard’s “Tuning BLs A-Series Engine” lying around, so that’s the guide I used.
Tungsten carbide cutters in a die grinder make short work of shaping the cast iron head. Grinding wheels are for sissies.
Once the basic porting and combustion chamber shaping was done, the head was sent back to the engine rebuilders to have the new unleaded valve seats and valve guides installed.
A small obsession 