Buy the Spitfire headers and be done. Avoid the nonsense of modifying the stainless block huggers. The initial price difference is going to be be in negative territory really fast if you have someone else modify them to fit.
If your headers are going to be temporary until your next motor is done, but a set of cheap headers with the tubes already formed and in place. Cut off what you don't need and use the leftover somewhere else on the headers.
I had a narrowed stock tank with the pipes through the springs. It was low and the springs would hit the pipes. My future thought is eliminate the spare tire well and use a 62-65 Fairlane tank. I'm not a fan of fuel cells in the trunk.
A competent exhaust shop should have been able to do your exhaust. I am surprised you didn't use 340 HP manifolds on your car as they would flow a lot better than the 273 manifolds. Maybe Eberg or Yakima would have more experienced shops.
They are being produced near me in the Seattle area. Laysons did not buy the rights from Harold, they had another shop build a fixture off of a set of Spitfire headers.
Maddog headers are pretty nice. I have a set on my FE powered 64 Fairlane, they fit good, have 3/8" flanges and the welds are nice. I would give his Mopar headers a try.
Layson's is having these headers made locally in the Seattle area. They are direct copies of Spitfires that Layson's had a jig made from a few years ago. It costs a lot of money to prototype and go into production on a set of headers that you may only sell 100 sets of. I have talked at length...
Wait for the Spring thaw and take it to a performance oriented exhaust shop. The tail pipe going into the muffler seems like a big time restriction. It should have been expanded, slipped over the muffler and welded.
I was completely overwhelmed! Too much to see in one day. I set some front suspension items to the side. Going to get a slant 6 dist. for your HEI conversion. I also spied a box with some goodies already pulled for you. Ray is a cool guy with a warehouse full of great car parts.
I know for a fact that Harold did not make headers for Layson. Layson's had a header manufacturer local to me copy a set of Spitfires and stopped payment upon delivery. I have seen the fixtures and one reference set. If there is enough interest, I can get them made.
He got me too! Ordered them in August, after a couple weeks I called him and he said they box was damaged in shipping. Many unanswered phone calls later...I decided to file a postal fraud investigation on him. We'll see how it comes out.