Here's the first rocker arm installed. This is where the next problem appeared - there was insufficient clearance for the pushrods around the intake manifold casting. About half the pushrods go through a machined hole, the others just around the rough casting. Most cleared the machined holes (but were clearly off center), but about half rubbed on the casting. One was so bad it pushed the rocker off it's stop by better than an eighth of an inch. My net conclusion was that the mainifold was set forward about 1/6" further than it should be. I tried "forcing" the manifold to the rear, but could not gain sufficient clearance. I decided it was time to cut the losses and "scrap" this manifold in favor of a new one. I took this one off and ordered a new 390 Performer manifold from Edelbrock.