Replaced Moen wall single lever (flow & temperature control) faucet (1986). All appeared to go well but my single lever control is reversed, left (counter clockwise) is now cold and right (clockwise) is hot. Did I install it upside down or something?

Most likely yes, there should be a small H/C on the top of the faceof the cartridge, see if its down. Whatever you find try rotating it 180 degrees, that should do it

Bob's referring to the stem part of the cartridge.
Pop the cover off the handle and remove it. Now rotate the flat part of the stem so the bottom is on top. Reassemble and test. Cold on the right now? Cheers, Tom

Does the handle pull out then turn left and right, or does the handle turn counter clockwise from the six oclock position? Bob is correct about checking for the hc, it should be on top if this is not a pull type cartridge. If it is a pull type, then Tom hit it, all you need to do is remove the handle, rotate only the stem 180.