Thank you Gokul, JB, SB and all for the information.
Yes as you said the kings of the earlier days were very flexible in religoius matters. Father in one religion and son in another. We know that kings patronized vaishnavism and built temples. Kundavai for that matter built sundara chozha vinnagaram and also a jain temple (neminathar). Cholas patronized Buddhism as well. Naagapattinam chudamani viharam.
Some more info: The famous temple at Thiruvarur had huge landed property donated by the Chola kings.
I got from net that King Nandivarma Pallava was a vaishnavite and he built many vishnu temples. He built the temple at Kuram a village or Agrahaaram 12 miles west of Kanchipuram. (see JB's mail)