Yes, you might still see some pH drift upward, but if it does and you get to a pH of 7.4-7.5 with your TA of 80, then I would expect the drift to slow down to the point it is manageable or maybe even seem to stop. Keep me posted and let me know what happens. If the drift is slower, but still too much to your liking, you can still go a little further down in TA to 70 or even 60 if you like, but I wouldn't go any further down than that. I suspect that 80 will be fine for you, but don't try to keep the pH at 7.2 (7.4-7.5 should be fine) unless is naturally doesn't drift upward anymore.

I'm keeping my fingers crossed for you.

Richard