OK, Don, the solenoid does not have a "field". It has terminals on both
sides of the switch it activates, and one terminal to the coil that causes
it to activate, which can be a ¼" flat blade or a screw binding post that
takes a ring terminal with a nut (on older starters). It may have another
small terminal that becomes "hot" when the solenoid is activated, and if the
car's wiring is made for such a feature, the wire from that terminal goes
to the coil, bypassing the ballast resistor. The other connection to the
solenoid's coil is through ground. None of these are a "field" terminal and
all the field terminals in the starter are internal and very heavy wiring.

You're going to have to bite the bullet and find out which wire is activated
when you turn the switch to "start" and make sure that one is on the starter's
"start" or activation terminal. It should not be a very big wire and should
have the same kind of terminal that the starter wants, probably a ¼" faston
terminal. Most of the other wires hooking to the big bolt are to furnish
power to various parts of the electrical system and they will usually be red.
They will also usually have a 5/16" or 8mm ring terminal to fit over the long
bolt connection on the starter.

If I read your diagnostic procedure correctly you have pretty much exonerated
both the motor and the solenoid activation but condemned the switching function
of the solenoid. Until that solenoid can pass 150 amps reliably when activated,
your starter is not going to crank, so you might as well fix that first. Then
when you get the starter put in and the wiring sorted out you will be able to
crank your engine with it.
--
George Downs Bartlesville, Heart of the USA!