I believe there's a PCI version of the Inno3D (clueless on the rep. of this manf.) FX5600 and FX5700LE. Not sure either were trimmed down to 64bit either though.
The Inno3D FX5700LE 256MB is apparently 256bit as per this vendor.
Vendor rating: http://www.resellerratings.com/seller2027.html
Hope this helps.