I am looking for a true homonym that has different spellings and
complete opposite meanings.

Hi spracky,

"The homonyms "raise" and "raze" have opposite meanings:
to build up and to tear down."
://www.google.ca/search?q=cache:Kt3sycP9XHAC:www.nickshumor.net/archive/humor/1998/msg00233.html+homonyms+%22opposite+meanings%22&hl=en&ie=UTF-8

Hoping this is what you are looking for. If this doesn't satisfy your
request, please post a clarification before rating my answer.

Thank you,
hummer

Search Strategy:
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Terms Used:
homonyms 
"opposite meanings"

Perfect--Thank you

I can't think of any other good homonym pairs, but I do have some
trivia to add: There are also a number of cases where one word can
have opposite meanings. For example, "dust" as a verb can mean either
to sprinkle dust on something or to remove dust from something.

Another bit of trivia:

A word which sounds exactly like another word, but which is spelling
differently and has an opposite meaning, is technically called a
homophonic, heterographic antonym.

Thank you, spracky.

hummer