Tim, not be be argumentative, but you and I live in two different worlds. I would (or could) never spend $10,000 building a flathead. The last one I did (2 years ago), was around $2100 with new pistons. a reground crank, and a MAX-1, finished off with vintage used speed equipment. It seems to me that lately, a lot of ancillary stuff we need (such as the aforementioned PTFE sealer), have become "boutique items" sold at extreme prices by some of the specialty dealers. For some of us, scrounging and networking allow us to do a quality job on a shoestring. A good example is the sealer mentioned. I was talking to a friend who is a union pipe fitter a few years ago, and the conversation came around to the aforementioned sealer. He said, "Do you need some?". When I answered in the affirmative, he gave me a peanut butter jar full. He also threw in about 6 rolls of Teflon tape, just to be sure.
A $10,000 flathead is a luxury item, pure and simple. If you are chasing performance, there are a myriad of ways to get a lot more for a lot less. A good performing, good looking engine can be put together for a lot less. Don't get me wrong; I really like to see these top end builds, but a lot of us just can't afford them.