Dan, it all depends on your skill level. If you have limited experience and skill, then the Mikuni VM that Lancer sells is your best choice. The kit he puts together has everything you need to install the carburetor, and there are lots of forum members running the VM, so help and advice will be plentiful.
The Keihin PWK works great but you have to gather up the parts piecemeal. It's a lot cheaper but you have to do the extra work gathering parts. The throttle cable is also is a bit more difficult to set up.
Both of the carbs work extremely well. The Keihin flows a bit more air so you get just a bit more power. The Mikuni is a bit more versatile in the tuning department because it has a removable needle jet and main air bleed. However both carbs are very easy to dial in.
I have run the VM38, PWK38 and PWK36 all with excellent results.
This post will give you some insight on how the VM & PWK compare to each other.
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1585461605And this post will provide a little more detail on installing a PWK38 on a stock engine. It will also give you a good baseline for jets and an idea of what to expect in terms of performance.
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1625732492 No matter what you choose, stock, VM or PWK, I'm sure the folks on this forum stand ready to help you get it up & runnin.
Good luck, Mike