Drilling new bolt pattern onto rear rotors?

Alright, so I am going to be building a 44 front, and will either have 5 on 5.5 or 6 lug, so I am getting custom Moser alloy shafts for the rear to match. I am curious what to do about the discs in the rear? I dont have them in there yet, but I figure why not do the disc swap now while I have the opportunity to put teh new rubi retainers on with the new wheel bearings. I will be putting in crown vic discs, and have an Xj 44.
All that said, what should I do about the new bolt pattern for the rear? Can I drill it out myself and get it centered enough? Should I send it to a machine shop and have them do it so I dont screw it up? I know if I get 5 on 5.5 in the front I could buy the teraflex rotors but I would rather not have to buy those if I dont have to. Curious to hear what you guys think.
josh

Wouldn't that cause some balanceing problems?

I dont know thats why I am asking!
If it would, what kind of discs will I need to get?
Anyone have insight on this?

I would opt for the machine shop. It's cheaper than doing it yourself, screwing it up, having to buy new ones and having the machine shop do it anyway.

Neil