Either get the lady (woud be bride) to adopt Hinduism and marry as per Hindu Marriage Act, 1955 or
Get the marriage performed / registered under the provisions of Special Marriage Act,1954.
It would be better to contact and consult a local prudent lawyer for proper guidance and proceeding.
However, if you are located in Delhi and feel, you may contact me (on appointment) at:
Chamber No 647, Lwayer's Chamber Block, Dwarka Courts Complex, Sector 10, Dwarka, New Delhi Cell # +91 9891152939 email: email@example.com