Where does the open face point to? Is it the intake valve?
I'm working on porting a set of E7 heads for my '85 project car. I have them off so it's easy to do. I just forget where the open face of the plug was supposed to point at.
It doesn't matter that much as long as it is facing towards the valves. Indexing prevents the spark from being shrowded. I thought it was towards the intake valve, but was never that sure.
Because spark plugs threads are not machined exactly, by trying different plugs in different holes you should be able to get it right, just a little time consuming.