Absolutely, #1 determinant of paste is pH when you scoop the curds, and to a lesser degree, pH at renneting.
What paste are you targetting? How runny? pH values are not absolute, they are used to help target specific cheese attributes?
Usually, tallegio is rennetted at 6.4 (Peter's 30-minute window for pre-ripening is too short unless the milk is old or you are making it from goat milk), and scooped at 6.2-6.25. This gives you enough runniness but not too much. You need a PF target of about .85-.9 in the milk. If you have a higher PF, say .95 or 1, it will be more runny.
Also, how will moving ph at these critical points affect the final paste?
pH at scoop is most important. Higher pH at scoop = more colloidal calcium in the micelles = more stable and firm paste.
What happens if I use Abiasa's Thermophile Type C
You will get a different flavor, slightly sweeter. pH curve will be slower, too.