I'd talk to a Ford dealer parts place, your hub looks identical to my 93, but I'm fairly certain mine are metallic. They are very thin.
Late thought, those hubs may be available only as a unit
Also be sure to line the cog in the cam assembly up with the slot in the spindle when you go to pop it on. Sometimes it can be rather stubborn but do not try forcing it, replacements are very expensive. I use a piece off the front of an old aluminum flashlight that was ruined by batteries being left in it for 25 years, the small end of the lens assembly is a great fit, and pop it on (if it's being stubborn), with a simple(not dead blow) rubber mallet
I think a milk jug would be the wrong plastic, I'm not sure what yours would look or be like, as I've never worked with those type, but they must be a special type plastic. At the minimum I'd try something microwavable.
I once made a little plastic washer using a nail, a ruler, the lid from a ranch dip plastic container, and a hobby knife. Drive the nail through the center of the lid into a wooden work top. Place it near the edge so you can work with it. Place the knife on the outside diameter you need and pull the lid in a circle until it's cut all around. Then cut the inside diameter the same way. Worked great.
Still, I believe you'll find most common plastics are not up to par with whatever one they used, especially where heat or friction are concerned
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