I have a converted Saiga 7.62 and I was thinking of installing a QD swivel mount on the left rear side of the reciever. I was thinking of using the holes from the old trigger rivets. Has anyone done this before? I've been looking at the the following:

This would require a 1/2" hole to be drilled, I was considering expanding the rear pin hole.
http://www.shopnoveske.com/products/flush-qd-sling-mount

I would like to use this one, but you have to drill it out also and I don't think I could get the holes to line up:
http://store.magpul.com/product/MAG528/188

This would be ideal, but the screws are pinned to the nuts.
http://www.midwayusa.com/product/597532/noveske-push-button-quick-detach-sling-mount-for-nsr-handguards-ar-15-aluminum-black

Posibly this one?
http://jerkingthetrigger.com/2013/01/22/an-ode-to-the-qd-micro-flush-qd-sling-mount-n-slot/

What is your opinion?

Echo93 V3/QD.  Easier:  http://jerkingthetrigger.com/2012/07/14/echo-nine-three-v3-qd-sling-plate/

 

Mine is a saiga conversion with a carolina shooters billet triggerguard and built in nut, I don't think that will work for me. I have considered cutting off the nut and replacing it with a standard one though.

Your first option looks cleanest  to me. And should be easiest to do. Use Red locktite