Trouble removing old wide-spread faucet
Our house is from 1970 and we have three of the exact same model faucets. The handle in particular is a bit rough on the hands so we were eager to replace. The drain cover says Price-Pfister.

Similar to above, the spanner nut was in there tight. On one of the replacements, I was able to use a type of hook wrench pictured to function as a way to hold it in place while I turned the underside of the spigot clockwise. This caused it to loosen. On another, I had to spray some WD40 on there to loosen it then once again hold it in place while I turned the underside of the spigot clockwise.

On both there was no budging the top assembly. Essentially you have to loosen it enough to be able to pull and expose enough spigot to take a mini hacksaw and saw it a little more than halfway. It takes about 10 minutes. After that it bends and breaks rather easily. Fortunately I did not need to break out the Dremel tool.