First off Welcome to AF!!!! I own a 90 century and well as far as advice goes you need to visit
http://cgi.a-body.net/forum and create an account there, their are some great people on that forum and will gladly give you as much help as they can, although it is a sort of slow forum but like I said VERY helpful people on it.
Also you said you had ordered a body kit, WHERE FROM and WHO MAKES IT? I've driven myself stupid tryin to find one for mine but I've had no luck with it.
I have the 3300 in mine and I must say it isn't all that fast but runs very well, you can take the route that I took on my old century before I flipped it, upgraded injectors, custom fuel rail, Dynomax exhaust, and a few other things that I can't remember right now.