I hope SV300 chimes in, he's done this before! But Im also planning to put some sort of good FR in my RG470 (OFR? FR Pro? Edge?!?!?!) and from what knowledge I've obtained in my research (most from SV300!) you'll need to switch the posts. And unfortunately that probably entails drilling out the holes a bit bigger and probably deeper as well. Preferably with a
drillpress!
As to getting the old bushings out you'll likely be pretty successful just getting some pliers and tugging at them til they pop. But if it really doesnt give then it might be glued in. In that case put a soldering iron in it to warm up and loosen the glue, and then remove, screw the stud back in, and go at it again with the pliers. But chances are it wont be glued at all. Be sure you measure out your cavity and post spacing though!
Also, you can just use the drill press and just drill out the old studs if you wish.