IMO,its best to set a head up for indexing while its off the block and you can see the comb chamber
then # the plug acordingly to the cyl
its free performance and a smoother running engine for some easy labor when puting one together
I have faced the plug opening towards the itake valve and have lined them all up in line with the little rectangle indent in the cc at the plug hole
but as stated...putting them in so the plug gap faces the expanding "wedge" makes for a complete burn and more leverage pushing down on the piston
thats why its called a "wedge head"