Assuming Garou didnt evolve mid fight :
I think Suiryu will win against early Garou : Garou was already strong and can beat a S class but Tank top was just brute strength and he was easy to read for Garou even if Tank top was stronger (sheer strength). Suiryu is S class level (low) he is physically strong and has great techniques too. Suiryu for the win.
For the second battle I think they are more or less equal. Garou learnt from fights with Metal Bat, whatchdog man, and the A class heroes.
Garou Stats were now improved and his techniques too (against weapons, bullets, animal moves etc).
I see them equal but Garou techniques are meant to deflect so he can maybe deflect Suiryu techniques but more over I think Garou's will and tenacity will alway grant him the win against someone at his level. And Suiryu has not the best will in history.
Garou win this very high diff maybe extreme.
Current manga Garou is likely too much of a beast : he fought against reaper and bug, h learnt Bomb techniques (iron cutting) he destroyed reaper, he fought low goons, fought Rover, and fought Orochi. He learnt a lot and became a total beast.
At this point I think he mid diff Suiryu if not less. Garou after Orochi fight when he recovered destroyed PPP.