Since I have a 7070 open on the bench right now, I can say that it would be quite easy compared to the G-9000 pictured.
Get something to use as a mounting plate...black plastic or Plexiglass. On the 7070 it looks like it would need to be about 3 1/4" wide by 2 1/2" tall. Remove the old wires and shitcan the spring connectors, align the new piece and mark it for the four mounting holes. Drill it, and install with new screws and nuts/lockwasher. For now, just install with one screw on top, and the other on bottom. Now from the rear mark the place to drill the plastic for the new gold posts. I'd suggest making them the proper width apart so that you can use one of
these should you choose to do so (which would mean that the '+' and '-' for each channel is 0.7" apart to accomodate a dual bananna plug). Remove the plastic, drill the holes, and install the binding posts.
I discovered that the stock rear 'washer' that comes with the binding post is a POS, and went to the hardware store and bought some nylon washers for the rear of the assembly. The stock ones tighten crookedly, and you lose the 0.7" spacing.
After the posts are installed and before you bolt it in, resolder all the wires. You will need a short length of 18ga wire to join the Neg terminals, but the Pos should be OK. You will also need a decent 20 - 25W soldering iron, and some electronic soldering flux to smear on the ass-end of the binding posts to aid in soldering the wires. Why? Because without the flux, you will be holding the iron on the post so long to get the solder flowing you will melt the plastic washers on the front and rear of the posts. You need to get it soldered and get the hell out of there before things start to overheat.
That's it. Mount the new terminal board and admire your work.