I've used the Autometer 9117 in a (Connecting to an Individual Coil Per Plug Ignition System) like Gaz mentioned.
Your just hooking up to one coil. Listed at the top of page 4.
http://www.autometer.com/media/manual/2650-561X.pdf
On the Tach, on the Smiths instructions if you are pulling a signal from one Coil pack the PPR for an 8 cyl = 4 or 1010000 dip swt setting
https://www.caigauge.com/documents//...-tacho-360.pdf
But thinking back,,, Since your pulling a single cyl signal the One cyl may be correct. PPR= .5 or 0000000.