How to torque a ZS manifold?

["Steve Gorr" <sgorr2@comcast.net>]

I replaced a cracked head on the 78 B over the winter. And I'd like to know
how one applies the proper torque to the middle 2 nuts on a ZS combo
intake/exhaust manifold. There doesn't seem to be a way to get a socket on
them so I've just used a box end. I fear I may have a vacuum leak since when
it did start it ran weak with backfires through the carb.