doing my daily search and came across this. I would jump on this but I believe my series 1 has different shaped exhaust ports. Hope this helps someone out.

http://atlanta.craigslist.org/sat/pts/2939442630.html

Ports didn't change to round shape until the N47 head in '77. N42 heads where "square" (if you call those things square) on 75/76, so that header will work for you just fine. Go for it man quick before someone else jumps on this now that you've let the cat (little exhaust joke there. hee hee....) out of the bag !