It's not as hard as you think. I did the "pseudo-AANJ" to a '93 RG550 that had the standard neck plate, 4 bolt thing. You should do it! It's fun and it feels so much better than having that block against your palm.
As far as filling the old holes, no, I bought neck attachment screw ferrules-ferulles (?) & used the exsisting holes of the upper right, lower right & lower left screws. The new upper left hole I had to drill, the old upper left hole was cut off when I rounded that corner off the body. You also need to counter sink the ferrules with a counterbore or I forget what it's called right now, but it cuts a hole with a nice flat bottom.
I did have to buy shorter screws too, I just picked them up at Home Depot, I brought the old screws with so I could match the threads up somewhat. I bought a thicker screw for the new hole, since I would be drilling it fresh anyway, I figured it would give added strength.
I'll try to post a picture for you.
Or go here :My Ibanez Mod