dear deeptha
I would suggest u name him Sudarshana or even Srivatsa or Srinatha. Giridhara rfers to Krishna holding the giri to save the residents of gokula. Hayagreeva refes to Vishnu as god of knowledge with athe face of a horse.If you want to name him 'visist' it is good but do name him 'vasistha' as 'visist' sound out of place and very north indian. Vasistha maharishi himself would not like 'visist'.
All the best with your child and 'ayushmanbhava' to him.