ol blue, I saw your post in regard to headers for your Henry J. I am building Henry J Gasser with 350 but having trouble finding headers. Pictures you posted show me Advance Adaptor headers may work. On passenger side what is distance from front spark plug to very end of exhaust collector. Same measurement on driver side. That info would be very helpful. My engine sits back farther than yours so these measurements would help me a great deal . I am old norse in this forum.
On my car, the #4 plug and the #3 exhaust port are about in line with my axle so I measured from the axle centerline back to the collector joint and come up with about 17" on both sides. My firewall is set back about 5" and the toe boards slant back to within 2" of the door opening, on the inside. http://www.henryjcars.com/hjc58/von/r2/r2.html This car appears to have the same headers and I've seen another that the builder said the source for them.