For those interested in running a 3pt on a Nova, here is how I went about it.
I ordered a Specter Gear 3pt for a Mossberg 500. The kit comes with a sling plate to use with the Mossberg tube which I did not use. The Remington 870 and Mossberg 590 version would probably also work.
For the front attachment, I used a Nordic Components mag clamp with picatinny rail. The NC clamp requires some care when mounting on a Benelli extension as it has a cut out for a Benelli clamp but it's no big deal. Then I just mounted up a generic sling swivel that mounts on picatinny rails. I plan on switching over to a GGG Sling Thing with HD QD swivel.
Here is what it looks like:
Links:
http://www.spectergear.com/mossberg_500_cqb_sling.htm
http://www.cactustactical.com/osc/nordic-components-gauge-shotgun-extension-tube-clamp-with-rail-p-1377.html
In hindsight I should've just ordered this for the front:
http://www.tacticalshotgunner.com/mesa-tactical-magazine-clamp-with-optional-rails-and-sling-swive-p-147.html