I'd consider a byte to be like a mole: it's the base unit that we actually use, and it's proper to apply an SI prefix to, but it's defined as a specific multiple of a smaller unit (8 bits vs 6.02 * 10^^23 particles).

"Giga inches" sounds wrong for two reasons: first, that larger distances like that are customarily expressed in units more suited to their scale, and second, that that measurement system generally doesn't use SI-style prefixes.

"KiloCM" sounds wrong because you're applying two SI prefixes to one unit and using the wrong capitalization for both "centi" and "meter". kcm could technically be represented by the "dam" unit, although it's more common to show things in that scale just as meters.