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English simply doesn't make that distinction, dwiji.   We do have the two differences in pronunciation, but because we don't spell them, such differences are mostly controled by the placement of the consonants in the word, and we're mostly unaware of them.   (Just ask most Merkins whether they pronounce "water" with a 't' sound.)

We have a few diacritical marks even in English, though they're rarely employed.   The diaeresis reminds us (or would if anyone still used it) that "reïnvent is pronounced as three syllables, not two.   And in dictionaries and a few other reference works we use diacritical marks over vowels to show their quality—to show that "mop" and "mope" are pronounced differently, for example.   But not even in dictionaries do we mark the different qualities of the plosive consonants ('p', 't' and 'k' and their voiced equivalents).

For your purpose, I think you'll have to just invent some system.

I just checked my old copy of IPA symbols transcribed to ASCII.   Not even there is your need covered.