Dan I saved part one of the JCNA article about 4.2 head studs that might help you. If I had an e-mail I could probably scan it to you. I do not have part two that I assume was in the March-April 2011 issue but if part one helps you perhaps the JCNA could send you a copy of part two.
Not sure if your 71 has the second set of throttle butterflies in the intake manifold like my 68 did but I got a big boost in performance by removing the secondary butterflies so there is a straight shot for the fuel/air mixture into the engine rather than routing thru the smaller passages in the intake manifold and crossover pipe on the 68's.
David Barnes
68 E-Type FHC