Different Reverse for Forward?

[East Village]

I am running an auth server for purely DNS on the same machine as a web server.

the forward IP for ns1.nameserver.com is the reverse IP for the web
server (because it also sends mail and needs to have the reverse
associated with the product itself (www.example.com). The reverse and
the primary DNS for example.com is by our ISP.

So:
ns1.nameserver.com = 1.2.3.4 (my DNS server)
1.2.3.4 = www.example.com (my ISP DNS server)

Does this present any technical issues with BIND or DNS in general?

Any other suggestions?

Thanks is advance.

Jed