Drywall – What’s the best way to hang this large picture on insulated plasterboard

I would like to hang this fairly large framed picture on my living room wall. The frame measures 167x75cm, and weighs roughly 8.5kg. Both top and bottom of the frame had snapped previously (while being transported from abroad), and have recently been repaired by a local framing specialist. Here is a photo of the back of it – you can see the 4 metal braces where the repair took place:

The wall it needs to go on is a 9mm plasterboard with 30mm insulation board on top. As you can see in the photo the frame already has two D rings fixed to the frame for hanging from two hooks.

I would like to put any fixings into the studs which are 400mm apart. Unfortunately to get the picture in the centre of the room, both D rings fall more or less halfway between studs.

Would anyone be able to provide some advise on the most secure way to hang this please? The two options I've thought of are:

1. Rotate the D rings 90 degrees so they point each other, attach a cord/wire, and hang on two screws screwed into the 2 closest studs (roughly 200mm from each D ring)
2. Hang using 2 hooks to match the current position of the D rings, and fix into the plasterboard using some kind of drywall fixing.

If going for the cord/wire option, do I want to use a cord or wire? And should it be attached taut or with plenty of slack?

If fixing to drywall I would assume a metal spring toggle would be the most suitable – however I've never seen drywall fixings used where there is insulation board in front of the plasterboard, and not really visualise if that gets in the way of the fixing at all?

Also should I worry about the stability of the frame at all after the snap and repair? The braces look to be strong but I suppose the frame still won't have its full original strength?

Any advise would be much appreciated! I'm just really nervous that if not done properly, the picture will fall one day and knock someone out…