Speedmaster head hypothetical

Another part of it for me is……..I have to be able to actually complete the job and supply the finished heads to the customer.
So, I look at how much time can be invested and still get paid for all of it.
Agreed, Unless your building for a highly competitive class and money is no object, like I think it was Super Stock Hemi's where they sink like 20+ grand in labor per head to gain 600 rpms for better shift points. There's tons of easier low hanging fruit to make power especially these day.