"Not quite sure what you mean by 'wheel won't turn'."
The idea is to tighten the castle nut to the point that the bearings are seated at which point, because there is no more in-out room, they begin clamping the hub ie. wheel won't turn.

"when I have the crown nut tightened as per Bentley (backed off, etc.) the hub itself won't spin freely."
But it does turn SMOOTHLY with a minimum of effort showing that the bearings are no longer clamping the hub. And that's what you are aiming for.

"But with the wheel installed I can get about 3-5 seconds of spin before it stops. Does that mean I'm good?"
Yes. Seems about right. When you're back on the road and everything is seated after a few miles, you can check and make adjustments if necessary.

"I wonder if I should have ensured there was no residue from the old grease before I packed them?"
Nah. Get the car on the road and don't worry about it.

"Please understand that I didn't choose to post in this old thread because of the title in order to garner special attention."
There was no offense intended. Take a look at the top of the page at the selection box beside the "index for 4/2015 (current)". For whatever reason it will take the unsuspecting into the past where they may proceed to offer help.

"I'm not a mechanic and most jobs I post about are being tackled for the first time."
My concern was that you may get yourself in too deep for a beginner. And another 240 would be abandoned.
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1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.