Dick -
Titrets are pretty much universally agreed to be useless for red
wines. Some people feel they are reasonably accurate for whites.
Others have concluded they are inaccurate for whites as well. There
are test strips available now from Accuvin which are an alternative to
Titrets, which are claimed to work with both red and white wines.

Normally, much of the pre-fermentation SO2 dosage is lost during
fermentation. ML bacteria are pretty sensitive to SO2, but all you
can do is try. If fermentation was reasonably vigorous, and you
haven't added any Campden tablets since, I'd think your odds of
successful MLF are reasonably good.

Doug