In the 1970-1983 Haynes manual, the procedure for the 1800 front wheel bearings is the same as the 140s and early 240s. After cleaning and packing, tighten the nut to 45 ft-lbs to fully seat the bearing then back off 1/3rd turn. It says then tighten by 1 ft-lb and insert the cotter pin either there or if the castle nut is not aligned then to tighten further to the next closest slot.

The procedure in the later Haynes 240 manual (which I used to use in my 140) is slightly different, but should end up at pretty much the same spot. That extra 1 ft-lb step above is going to be tricky without a suitable and accurate torque wrench. The later Haynes procedure is simply to tighten to 50 ft-lbs, back off 1/3rd, then insert the cotter pin. Use the closest slot, either a little tighter (when in doubt I would lean that way) or a little looser (if fairly close).

Plus or minus one crown slot isn't going to make a whole lot of difference, it just may need readjustment a little sooner if you lean to the loose side.

Spin the wheel by hand after backing it off 1/3rd and then again after you're done. It should freely spin the same and there should be zero side play. Not doing it often enough and not always trusting myself, I used to spin the wheel a whole bunch of times and repeat the whole procedure to make sure the pin ended up in the same slot. Pack the grease cap about half full.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now