I'll throw in my two cents here FWIW / LOL / etc...
I suspect that the Borg would've been conceptually different in TOS, to suit the sensibilities and general worldviews of both the show's makers and the audience of that time. They woud've been nasty technology scavengers like what we saw in "Q Who", not the totalitarian race-devourers of "The Best of Both Worlds" and later.
If budgetary concerns would've had an effect on the appearance of the Borg, I would think they might've looked a little like a cross between the early Borg of "Q Who" and DOCTOR WHO's Cybermen.
I have always had my doubts, though, about the compatibility of the Borg concept with the STAR TREK Universe, TNG or no TNG. Whether they assimilated the bodies of their victims or not, the notion of a massive race of machine-beings marauding the Galaxy at warp speed for thousands of centuries would suggest to me that there shouldn't be much of the Galaxy left for Kirk and company to explore.